diff --git a/accessible/src/base/nsAccessible.cpp b/accessible/src/base/nsAccessible.cpp
index 4e2c732c5672..abe419a8f54f 100644
--- a/accessible/src/base/nsAccessible.cpp
+++ b/accessible/src/base/nsAccessible.cpp
@@ -1367,7 +1367,7 @@ NS_IMETHODIMP nsAccessible::GetBounds(PRInt32 *x, PRInt32 *y, PRInt32 *width, PR
 
   // We have the union of the rectangle, now we need to put it in absolute screen coords
 
-  nsRect orgRectPixels = aBoundingFrame->GetScreenRectExternal();
+  nsIntRect orgRectPixels = aBoundingFrame->GetScreenRectExternal();
   *x += orgRectPixels.x;
   *y += orgRectPixels.y;
 
diff --git a/accessible/src/base/nsCaretAccessible.cpp b/accessible/src/base/nsCaretAccessible.cpp
index 76e6cea922f3..4bcf3310742e 100644
--- a/accessible/src/base/nsCaretAccessible.cpp
+++ b/accessible/src/base/nsCaretAccessible.cpp
@@ -344,10 +344,10 @@ nsCaretAccessible::SpellcheckSelectionChanged(nsIDOMDocument *aDoc,
   return mRootAccessible->FireAccessibleEvent(event);
 }
 
-nsRect
+nsIntRect
 nsCaretAccessible::GetCaretRect(nsIWidget **aOutWidget)
 {
-  nsRect caretRect;
+  nsIntRect caretRect;
   NS_ENSURE_TRUE(aOutWidget, caretRect);
   *aOutWidget = nsnull;
   NS_ENSURE_TRUE(mRootAccessible, caretRect);
@@ -375,28 +375,27 @@ nsCaretAccessible::GetCaretRect(nsIWidget **aOutWidget)
   nsCOMPtr<nsISelection> caretSelection(do_QueryReferent(mLastUsedSelection));
   NS_ENSURE_TRUE(caretSelection, caretRect);
   
+  nsRect rect;
   caret->GetCaretCoordinates(nsCaret::eRenderingViewCoordinates, caretSelection,
-                             &caretRect, &isCollapsed, &view);
-  if (!view || caretRect.IsEmpty()) {
-    return nsRect(); // Return empty rect
+                             &rect, &isCollapsed, &view);
+  if (!view || rect.IsEmpty()) {
+    return nsIntRect(); // Return empty rect
   }
 
   PRBool isVisible;
   caret->GetCaretVisible(&isVisible);
   if (!isVisible) {
-    return nsRect();  // Return empty rect
+    return nsIntRect();  // Return empty rect
   }
   nsPoint offsetFromWidget;
   *aOutWidget = view->GetNearestWidget(&offsetFromWidget);
-  NS_ENSURE_TRUE(*aOutWidget, nsRect());
+  NS_ENSURE_TRUE(*aOutWidget, nsIntRect());
 
   nsPresContext *presContext = presShell->GetPresContext();
-  NS_ENSURE_TRUE(presContext, nsRect());
+  NS_ENSURE_TRUE(presContext, nsIntRect());
 
-  caretRect.x = presContext->AppUnitsToDevPixels(caretRect.x + offsetFromWidget.x);
-  caretRect.y = presContext->AppUnitsToDevPixels(caretRect.y + offsetFromWidget.y);
-  caretRect.width = presContext->AppUnitsToDevPixels(caretRect.width);
-  caretRect.height = presContext->AppUnitsToDevPixels(caretRect.height);
+  rect += offsetFromWidget;
+  caretRect = nsRect::ToOutsidePixels(rect, presContext->AppUnitsPerDevPixel());
 
   (*aOutWidget)->WidgetToScreen(caretRect, caretRect);
 
diff --git a/accessible/src/base/nsCaretAccessible.h b/accessible/src/base/nsCaretAccessible.h
index 9fcc96343b5e..6c0221c5fbd2 100644
--- a/accessible/src/base/nsCaretAccessible.h
+++ b/accessible/src/base/nsCaretAccessible.h
@@ -119,7 +119,7 @@ public:
    */
   nsresult RemoveDocSelectionListener(nsIPresShell *aShell);
 
-  nsRect GetCaretRect(nsIWidget **aOutWidget);
+  nsIntRect GetCaretRect(nsIWidget **aOutWidget);
 
 protected:
   nsresult NormalSelectionChanged(nsIDOMDocument *aDoc, nsISelection *aSel);
diff --git a/accessible/src/html/nsHTMLAreaAccessible.cpp b/accessible/src/html/nsHTMLAreaAccessible.cpp
index b31fccb265c6..0097c8e77c34 100644
--- a/accessible/src/html/nsHTMLAreaAccessible.cpp
+++ b/accessible/src/html/nsHTMLAreaAccessible.cpp
@@ -149,7 +149,8 @@ nsHTMLAreaAccessible::GetBounds(PRInt32 *x, PRInt32 *y,
   imageFrame->GetImageMap(presContext, getter_AddRefs(map));
   NS_ENSURE_TRUE(map, NS_ERROR_FAILURE);
 
-  nsRect rect, orgRectPixels;
+  nsRect rect;
+  nsIntRect orgRectPixels;
   rv = map->GetBoundsForAreaContent(ourContent, presContext, rect);
   NS_ENSURE_SUCCESS(rv, rv);
 
diff --git a/accessible/src/html/nsHyperTextAccessible.cpp b/accessible/src/html/nsHyperTextAccessible.cpp
index 982ade210682..475a00d2415f 100644
--- a/accessible/src/html/nsHyperTextAccessible.cpp
+++ b/accessible/src/html/nsHyperTextAccessible.cpp
@@ -301,13 +301,13 @@ nsIntRect nsHyperTextAccessible::GetBoundsForString(nsIFrame *aFrame, PRUint32 a
     // Add the point where the string starts to the frameScreenRect
     nsPoint frameTextStartPoint;
     rv = frame->GetPointFromOffset(startContentOffset, &frameTextStartPoint);
-    NS_ENSURE_SUCCESS(rv, nsRect());   
+    NS_ENSURE_SUCCESS(rv, nsIntRect());   
     frameScreenRect.x += context->AppUnitsToDevPixels(frameTextStartPoint.x);
 
     // Use the point for the end offset to calculate the width
     nsPoint frameTextEndPoint;
     rv = frame->GetPointFromOffset(startContentOffset + frameSubStringLength, &frameTextEndPoint);
-    NS_ENSURE_SUCCESS(rv, nsRect());   
+    NS_ENSURE_SUCCESS(rv, nsIntRect());   
     frameScreenRect.width = context->AppUnitsToDevPixels(frameTextEndPoint.x - frameTextStartPoint.x);
 
     screenRect.UnionRect(frameScreenRect, screenRect);
@@ -1346,12 +1346,12 @@ nsHyperTextAccessible::GetOffsetAtPoint(PRInt32 aX, PRInt32 aY,
   if (!frameScreenRect.Contains(coords.x, coords.y)) {
     return NS_OK;   // Not found, will return -1
   }
-  nsPoint pointInHyperText(coords.x - frameScreenRect.x,
+  nsIntPoint pxInHyperText(coords.x - frameScreenRect.x,
                            coords.y - frameScreenRect.y);
   nsPresContext *context = GetPresContext();
   NS_ENSURE_TRUE(context, NS_ERROR_FAILURE);
-  pointInHyperText.x = context->DevPixelsToAppUnits(pointInHyperText.x);
-  pointInHyperText.y = context->DevPixelsToAppUnits(pointInHyperText.y);
+  nsPoint pointInHyperText(context->DevPixelsToAppUnits(pxInHyperText.x),
+                           context->DevPixelsToAppUnits(pxInHyperText.y));
 
   // Go through the frames to check if each one has the point.
   // When one does, add up the character offsets until we have a match
diff --git a/content/base/src/nsImageLoadingContent.cpp b/content/base/src/nsImageLoadingContent.cpp
index f6f892841511..8b4a8937f73f 100644
--- a/content/base/src/nsImageLoadingContent.cpp
+++ b/content/base/src/nsImageLoadingContent.cpp
@@ -158,7 +158,7 @@ nsImageLoadingContent::~nsImageLoadingContent()
 NS_IMETHODIMP
 nsImageLoadingContent::FrameChanged(imgIContainer* aContainer,
                                     gfxIImageFrame* aFrame,
-                                    nsRect* aDirtyRect)
+                                    nsIntRect* aDirtyRect)
 {
   LOOP_OVER_OBSERVERS(FrameChanged(aContainer, aFrame, aDirtyRect));
   return NS_OK;
@@ -204,7 +204,7 @@ nsImageLoadingContent::OnStartFrame(imgIRequest* aRequest,
 NS_IMETHODIMP
 nsImageLoadingContent::OnDataAvailable(imgIRequest* aRequest,
                                        gfxIImageFrame* aFrame,
-                                       const nsRect* aRect)
+                                       const nsIntRect* aRect)
 {
   LOOP_OVER_OBSERVERS(OnDataAvailable(aRequest, aFrame, aRect));
   return NS_OK;
diff --git a/content/events/src/nsDOMUIEvent.cpp b/content/events/src/nsDOMUIEvent.cpp
index 47765ce90902..57bbf4c833bf 100644
--- a/content/events/src/nsDOMUIEvent.cpp
+++ b/content/events/src/nsDOMUIEvent.cpp
@@ -121,28 +121,32 @@ NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(nsDOMUIEvent)
   NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(UIEvent)
 NS_INTERFACE_MAP_END_INHERITING(nsDOMEvent)
 
-nsPoint nsDOMUIEvent::GetScreenPoint() {
+nsIntPoint
+nsDOMUIEvent::GetScreenPoint()
+{
   if (!mEvent || 
        (mEvent->eventStructType != NS_MOUSE_EVENT &&
         mEvent->eventStructType != NS_POPUP_EVENT &&
         mEvent->eventStructType != NS_MOUSE_SCROLL_EVENT &&
         mEvent->eventStructType != NS_DRAG_EVENT)) {
-    return nsPoint(0, 0);
+    return nsIntPoint(0, 0);
   }
 
   if (!((nsGUIEvent*)mEvent)->widget ) {
     return mEvent->refPoint;
   }
 
-  nsRect bounds(mEvent->refPoint, nsSize(1, 1));
-  nsRect offset;
+  nsIntRect bounds(mEvent->refPoint, nsIntSize(1, 1));
+  nsIntRect offset;
   ((nsGUIEvent*)mEvent)->widget->WidgetToScreen ( bounds, offset );
-  PRInt32 factor = mPresContext->DeviceContext()->UnscaledAppUnitsPerDevPixel();
-  return nsPoint(nsPresContext::AppUnitsToIntCSSPixels(offset.x * factor),
-                 nsPresContext::AppUnitsToIntCSSPixels(offset.y * factor));
+  nscoord factor = mPresContext->DeviceContext()->UnscaledAppUnitsPerDevPixel();
+  return nsIntPoint(nsPresContext::AppUnitsToIntCSSPixels(offset.x * factor),
+                    nsPresContext::AppUnitsToIntCSSPixels(offset.y * factor));
 }
 
-nsPoint nsDOMUIEvent::GetClientPoint() {
+nsIntPoint
+nsDOMUIEvent::GetClientPoint()
+{
   if (!mEvent ||
       (mEvent->eventStructType != NS_MOUSE_EVENT &&
        mEvent->eventStructType != NS_POPUP_EVENT &&
@@ -156,14 +160,14 @@ nsPoint nsDOMUIEvent::GetClientPoint() {
   nsPoint pt(0, 0);
   nsIPresShell* shell = mPresContext->GetPresShell();
   if (!shell) {
-    return pt;
+    return nsIntPoint(0, 0);
   }
   nsIFrame* rootFrame = shell->GetRootFrame();
   if (rootFrame)
     pt = nsLayoutUtils::GetEventCoordinatesRelativeTo(mEvent, rootFrame);
 
-  return nsPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
-                 nsPresContext::AppUnitsToIntCSSPixels(pt.y));
+  return nsIntPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
+                    nsPresContext::AppUnitsToIntCSSPixels(pt.y));
 }
 
 NS_IMETHODIMP
@@ -194,14 +198,14 @@ nsDOMUIEvent::InitUIEvent(const nsAString & typeArg, PRBool canBubbleArg, PRBool
 }
 
 // ---- nsDOMNSUIEvent implementation -------------------
-nsPoint
+nsIntPoint
 nsDOMUIEvent::GetPagePoint()
 {
   if (mPrivateDataDuplicated) {
     return mPagePoint;
   }
 
-  nsPoint pagePoint = GetClientPoint();
+  nsIntPoint pagePoint(GetClientPoint());
 
   // If there is some scrolling, add scroll info to client point.
   if (mPresContext && mPresContext->GetPresShell()) {
@@ -209,8 +213,8 @@ nsDOMUIEvent::GetPagePoint()
     nsIScrollableFrame* scrollframe = shell->GetRootScrollFrameAsScrollable();
     if (scrollframe) {
       nsPoint pt = scrollframe->GetScrollPosition();
-      pagePoint += nsPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
-                           nsPresContext::AppUnitsToIntCSSPixels(pt.y));
+      pagePoint += nsIntPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
+                              nsPresContext::AppUnitsToIntCSSPixels(pt.y));
     }
   }
 
@@ -306,7 +310,9 @@ nsDOMUIEvent::SetCancelBubble(PRBool aCancelBubble)
   return NS_OK;
 }
 
-nsPoint nsDOMUIEvent::GetLayerPoint() {
+nsIntPoint
+nsDOMUIEvent::GetLayerPoint()
+{
   if (!mEvent ||
       (mEvent->eventStructType != NS_MOUSE_EVENT &&
        mEvent->eventStructType != NS_POPUP_EVENT &&
@@ -323,9 +329,8 @@ nsPoint nsDOMUIEvent::GetLayerPoint() {
     return mLayerPoint;
   nsIFrame* layer = nsLayoutUtils::GetClosestLayer(targetFrame);
   nsPoint pt(nsLayoutUtils::GetEventCoordinatesRelativeTo(mEvent, layer));
-  pt.x =  nsPresContext::AppUnitsToIntCSSPixels(pt.x);
-  pt.y =  nsPresContext::AppUnitsToIntCSSPixels(pt.y);
-  return pt;
+  return nsIntPoint(nsPresContext::AppUnitsToIntCSSPixels(pt.x),
+                    nsPresContext::AppUnitsToIntCSSPixels(pt.y));
 }
 
 NS_IMETHODIMP
@@ -389,7 +394,7 @@ nsDOMUIEvent::DuplicatePrivateData()
   mLayerPoint = GetLayerPoint();
   mPagePoint = GetPagePoint();
   // GetScreenPoint converts mEvent->refPoint to right coordinates.
-  nsPoint screenPoint = GetScreenPoint();
+  nsIntPoint screenPoint(GetScreenPoint());
   nsresult rv = nsDOMEvent::DuplicatePrivateData();
   if (NS_SUCCEEDED(rv)) {
     mEvent->refPoint = screenPoint;
diff --git a/content/events/src/nsDOMUIEvent.h b/content/events/src/nsDOMUIEvent.h
index 275a4496e175..0ad95145102a 100644
--- a/content/events/src/nsDOMUIEvent.h
+++ b/content/events/src/nsDOMUIEvent.h
@@ -74,18 +74,18 @@ public:
 protected:
 
   // Internal helper functions
-  nsPoint GetClientPoint();
-  nsPoint GetScreenPoint();
-  nsPoint GetLayerPoint();
-  nsPoint GetPagePoint();
+  nsIntPoint GetClientPoint();
+  nsIntPoint GetScreenPoint();
+  nsIntPoint GetLayerPoint();
+  nsIntPoint GetPagePoint();
   
 protected:
   nsCOMPtr<nsIDOMAbstractView> mView;
   PRInt32 mDetail;
-  nsPoint mClientPoint;
+  nsIntPoint mClientPoint;
   // Screenpoint is mEvent->refPoint.
-  nsPoint mLayerPoint;
-  nsPoint mPagePoint;
+  nsIntPoint mLayerPoint;
+  nsIntPoint mPagePoint;
 };
 
 #define NS_FORWARD_TO_NSDOMUIEVENT \
diff --git a/content/events/src/nsEventListenerManager.cpp b/content/events/src/nsEventListenerManager.cpp
index 47b281edaa9d..c1ace7cff59c 100644
--- a/content/events/src/nsEventListenerManager.cpp
+++ b/content/events/src/nsEventListenerManager.cpp
@@ -1380,7 +1380,7 @@ nsEventListenerManager::FixContextMenuEvent(nsPresContext* aPresContext,
 
   // see if we should use the caret position for the popup
   if (contextMenuKey) {
-    nsPoint caretPoint;
+    nsIntPoint caretPoint;
     // Beware! This may flush notifications via synchronous
     // ScrollSelectionIntoView.
     if (PrepareToUseCaretPosition(((nsGUIEvent*)aEvent)->widget,
@@ -1413,7 +1413,7 @@ nsEventListenerManager::FixContextMenuEvent(nsPresContext* aPresContext,
 
   if (currentFocus) {
     // Reset event coordinates relative to focused frame in view
-    nsPoint targetPt;
+    nsIntPoint targetPt;
     GetCoordinatesFor(currentFocus, aPresContext, shell, targetPt);
     aEvent->refPoint.x = targetPt.x;
     aEvent->refPoint.y = targetPt.y;
@@ -1441,7 +1441,7 @@ nsEventListenerManager::FixContextMenuEvent(nsPresContext* aPresContext,
 PRBool
 nsEventListenerManager::PrepareToUseCaretPosition(nsIWidget* aEventWidget,
                                                   nsIPresShell* aShell,
-                                                  nsPoint& aTargetPt)
+                                                  nsIntPoint& aTargetPt)
 {
   nsresult rv;
 
@@ -1534,7 +1534,7 @@ nsEventListenerManager::PrepareToUseCaretPosition(nsIWidget* aEventWidget,
   widgetView->GetNearestWidget(&viewToWidget);
   nsPoint viewDelta = view->GetOffsetTo(widgetView) + viewToWidget;
 
-  // caret coordinates are in twips, convert to pixels
+  // caret coordinates are in app units, convert to pixels
   nsPresContext* presContext = aShell->GetPresContext();
   aTargetPt.x = presContext->AppUnitsToDevPixels(viewDelta.x + caretCoords.x + caretCoords.width);
   aTargetPt.y = presContext->AppUnitsToDevPixels(viewDelta.y + caretCoords.y + caretCoords.height);
@@ -1548,7 +1548,7 @@ void
 nsEventListenerManager::GetCoordinatesFor(nsIDOMElement *aCurrentEl, 
                                           nsPresContext *aPresContext,
                                           nsIPresShell *aPresShell, 
-                                          nsPoint& aTargetPt)
+                                          nsIntPoint& aTargetPt)
 {
   nsCOMPtr<nsIContent> focusedContent(do_QueryInterface(aCurrentEl));
   aPresShell->ScrollContentIntoView(focusedContent,
diff --git a/content/events/src/nsEventListenerManager.h b/content/events/src/nsEventListenerManager.h
index f78eac05b9eb..e4982b9f6685 100644
--- a/content/events/src/nsEventListenerManager.h
+++ b/content/events/src/nsEventListenerManager.h
@@ -181,9 +181,9 @@ protected:
                                nsIDOMEvent** aDOMEvent);
   PRBool PrepareToUseCaretPosition(nsIWidget* aEventWidget,
                                    nsIPresShell* aShell,
-                                   nsPoint& aTargetPt);
+                                   nsIntPoint& aTargetPt);
   void GetCoordinatesFor(nsIDOMElement *aCurrentEl, nsPresContext *aPresContext,
-                         nsIPresShell *aPresShell, nsPoint& aTargetPt);
+                         nsIPresShell *aPresShell, nsIntPoint& aTargetPt);
   nsresult GetDOM2EventGroup(nsIDOMEventGroup** aGroup);
   PRBool ListenerCanHandle(nsListenerStruct* aLs, nsEvent* aEvent);
 
diff --git a/content/events/src/nsEventStateManager.cpp b/content/events/src/nsEventStateManager.cpp
index 1957bfb2b362..12c0d86dbd3f 100644
--- a/content/events/src/nsEventStateManager.cpp
+++ b/content/events/src/nsEventStateManager.cpp
@@ -313,7 +313,7 @@ public:
   static void EndTransaction();
   static void OnEvent(nsEvent* aEvent);
 protected:
-  static nsPoint GetScreenPoint(nsGUIEvent* aEvent);
+  static nsIntPoint GetScreenPoint(nsGUIEvent* aEvent);
   static PRUint32 GetTimeoutTime();
   static PRUint32 GetIgnoreMoveDelayTime();
 
@@ -385,7 +385,7 @@ nsMouseWheelTransaction::OnEvent(nsEvent* aEvent)
       if (((nsMouseEvent*)aEvent)->reason == nsMouseEvent::eReal) {
         // If the cursor is moving to be outside the frame,
         // terminate the scrollwheel transaction.
-        nsPoint pt = GetScreenPoint((nsGUIEvent*)aEvent);
+        nsIntPoint pt(GetScreenPoint((nsGUIEvent*)aEvent));
         nsIntRect r = sTargetFrame->GetScreenRectExternal();
         if (!r.Contains(pt)) {
           EndTransaction();
@@ -416,13 +416,13 @@ nsMouseWheelTransaction::OnEvent(nsEvent* aEvent)
   }
 }
 
-nsPoint
+nsIntPoint
 nsMouseWheelTransaction::GetScreenPoint(nsGUIEvent* aEvent)
 {
   NS_ASSERTION(aEvent, "aEvent is null");
   NS_ASSERTION(aEvent->widget, "aEvent-widget is null");
-  nsRect tmpRect;
-  aEvent->widget->WidgetToScreen(nsRect(aEvent->refPoint, nsSize(1, 1)),
+  nsIntRect tmpRect;
+  aEvent->widget->WidgetToScreen(nsIntRect(aEvent->refPoint, nsIntSize(1, 1)),
                                  tmpRect);
   return tmpRect.TopLeft();
 }
@@ -1885,8 +1885,8 @@ nsEventStateManager::BeginTrackingDragGesture(nsPresContext* aPresContext,
 {
   // Note that |inDownEvent| could be either a mouse down event or a
   // synthesized mouse move event.
-  nsRect screenPt;
-  inDownEvent->widget->WidgetToScreen(nsRect(inDownEvent->refPoint, nsSize(1, 1)),
+  nsIntRect screenPt;
+  inDownEvent->widget->WidgetToScreen(nsIntRect(inDownEvent->refPoint, nsIntSize(1, 1)),
                                       screenPt);
   mGestureDownPoint = screenPt.TopLeft();
 
@@ -1929,7 +1929,7 @@ nsEventStateManager::FillInEventFromGestureDown(nsMouseEvent* aEvent)
   // Set the coordinates in the new event to the coordinates of
   // the old event, adjusted for the fact that the widget might be
   // different
-  nsRect tmpRect(0, 0, 1, 1);
+  nsIntRect tmpRect(0, 0, 1, 1);
   aEvent->widget->WidgetToScreen(tmpRect, tmpRect);
   aEvent->refPoint = mGestureDownPoint - tmpRect.TopLeft();
   aEvent->isShift = mGestureDownShift;
@@ -1990,10 +1990,10 @@ nsEventStateManager::GenerateDragGesture(nsPresContext* aPresContext,
     }
 
     // fire drag gesture if mouse has moved enough
-    nsRect tmpRect;
-    aEvent->widget->WidgetToScreen(nsRect(aEvent->refPoint, nsSize(1, 1)),
+    nsIntRect tmpRect;
+    aEvent->widget->WidgetToScreen(nsIntRect(aEvent->refPoint, nsIntSize(1, 1)),
                                    tmpRect);
-    nsPoint pt = tmpRect.TopLeft();
+    nsIntPoint pt(tmpRect.TopLeft());
     if (PR_ABS(pt.x - mGestureDownPoint.x) > pixelThresholdX ||
         PR_ABS(pt.y - mGestureDownPoint.y) > pixelThresholdY) {
 #ifdef CLICK_HOLD_CONTEXT_MENUS
diff --git a/content/events/src/nsEventStateManager.h b/content/events/src/nsEventStateManager.h
index 7a85fc284638..57e5c0df390b 100644
--- a/content/events/src/nsEventStateManager.h
+++ b/content/events/src/nsEventStateManager.h
@@ -385,7 +385,7 @@ protected:
   nsWeakFrame mLastDragOverFrame;
 
   // member variables for the d&d gesture state machine
-  nsPoint mGestureDownPoint; // screen coordinates
+  nsIntPoint mGestureDownPoint; // screen coordinates
   // The content to use as target if we start a d&d (what we drag).
   nsCOMPtr<nsIContent> mGestureDownContent;
   // The content of the frame where the mouse-down event occurred. It's the same
diff --git a/content/events/src/nsQueryContentEventHandler.cpp b/content/events/src/nsQueryContentEventHandler.cpp
index 0116679bda53..fdcd34a0168b 100644
--- a/content/events/src/nsQueryContentEventHandler.cpp
+++ b/content/events/src/nsQueryContentEventHandler.cpp
@@ -437,25 +437,25 @@ nsQueryContentEventHandler::QueryRectFor(nsQueryContentEvent* aEvent,
   rv = frame->GetPointFromOffset(aRange->StartOffset(), &posInFrame);
   NS_ENSURE_SUCCESS(rv, rv);
 
-  aEvent->mReply.mRect.y = posInFrame.y;
-  aEvent->mReply.mRect.height = frame->GetSize().height;
+  nsRect rect;
+  rect.y = posInFrame.y;
+  rect.height = frame->GetSize().height;
 
   if (aEvent->message == NS_QUERY_CHARACTER_RECT) {
     nsPoint nextPos;
     rv = frame->GetPointFromOffset(aRange->EndOffset(), &nextPos);
     NS_ENSURE_SUCCESS(rv, rv);
-    aEvent->mReply.mRect.x = PR_MIN(posInFrame.x, nextPos.x);
-    aEvent->mReply.mRect.width = PR_ABS(posInFrame.x - nextPos.x);
+    rect.x = PR_MIN(posInFrame.x, nextPos.x);
+    rect.width = PR_ABS(posInFrame.x - nextPos.x);
   } else {
-    aEvent->mReply.mRect.x = posInFrame.x;
-    aEvent->mReply.mRect.width = aCaret->GetCaretRect().width;
+    rect.x = posInFrame.x;
+    rect.width = aCaret->GetCaretRect().width;
   }
 
-  // The coordinates are app units here, they will be converted to system
-  // coordinates by view manager.
-  rv = ConvertToRootViewRelativeOffset(frame, aEvent->mReply.mRect);
+  rv = ConvertToRootViewRelativeOffset(frame, rect);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  aEvent->mReply.mRect = nsRect::ToOutsidePixels(rect, mPresContext->AppUnitsPerDevPixel());
   aEvent->mSucceeded = PR_TRUE;
   return NS_OK;
 }
@@ -504,9 +504,11 @@ nsQueryContentEventHandler::OnQueryCaretRect(nsQueryContentEvent* aEvent)
     NS_ENSURE_SUCCESS(rv, rv);
     if (offset == aEvent->mInput.mOffset) {
       PRBool isCollapsed;
+      nsRect rect;
       rv = caret->GetCaretCoordinates(nsCaret::eTopLevelWindowCoordinates,
-                                      mSelection, &aEvent->mReply.mRect,
+                                      mSelection, &rect,
                                       &isCollapsed, nsnull);
+      aEvent->mReply.mRect = nsRect::ToOutsidePixels(rect, mPresContext->AppUnitsPerDevPixel());
       NS_ENSURE_SUCCESS(rv, rv);
       aEvent->mSucceeded = PR_TRUE;
       return NS_OK;
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index 5597626000a4..5b63329d5eff 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -5495,7 +5495,7 @@ nsDocShell::CaptureState()
             if (rootView) {
                 nsIWidget *widget = rootView->GetWidget();
                 if (widget) {
-                    nsRect bounds(0, 0, 0, 0);
+                    nsIntRect bounds(0, 0, 0, 0);
                     widget->GetBounds(bounds);
                     rv = mOSHE->SetViewerBounds(bounds);
                 }
@@ -5820,7 +5820,7 @@ nsDocShell::RestoreFromHistory()
     // bounds of the root view's widget.
 
     nsIView *rootViewSibling = nsnull, *rootViewParent = nsnull;
-    nsRect newBounds(0, 0, 0, 0);
+    nsIntRect newBounds(0, 0, 0, 0);
 
     nsCOMPtr<nsIPresShell> oldPresShell;
     nsDocShell::GetPresShell(getter_AddRefs(oldPresShell));
@@ -5876,7 +5876,7 @@ nsDocShell::RestoreFromHistory()
     }
 
     // get the previous content viewer size
-    nsRect oldBounds(0, 0, 0, 0);
+    nsIntRect oldBounds(0, 0, 0, 0);
     mLSHE->GetViewerBounds(oldBounds);
 
     // Restore the refresh URI list.  The refresh timers will be restarted
@@ -6450,7 +6450,7 @@ nsDocShell::SetupNewViewer(nsIContentViewer * aNewViewer)
     nsCOMPtr<nsIWidget> widget;
     NS_ENSURE_SUCCESS(GetMainWidget(getter_AddRefs(widget)), NS_ERROR_FAILURE);
 
-    nsRect bounds(x, y, cx, cy);
+    nsIntRect bounds(x, y, cx, cy);
 
     if (NS_FAILED(mContentViewer->Init(widget, bounds))) {
         mContentViewer = nsnull;
diff --git a/docshell/base/nsDocShell.h b/docshell/base/nsDocShell.h
index 747acf880a2d..a3d1d77a98a2 100644
--- a/docshell/base/nsDocShell.h
+++ b/docshell/base/nsDocShell.h
@@ -620,7 +620,7 @@ protected:
     nsCOMPtr<nsISupportsArray> mRefreshURIList;
     nsCOMPtr<nsISupportsArray> mSavedRefreshURIList;
     nsRefPtr<nsDSURIContentListener> mContentListener;
-    nsRect                     mBounds; // Dimensions of the docshell
+    nsIntRect                  mBounds; // Dimensions of the docshell
     nsCOMPtr<nsIContentViewer> mContentViewer;
     nsCOMPtr<nsIDocumentCharsetInfo> mDocumentCharsetInfo;
     nsCOMPtr<nsIWidget>        mParentWidget;
@@ -633,7 +633,7 @@ protected:
     nsCOMPtr<nsISHistory>      mSessionHistory;
     nsCOMPtr<nsIGlobalHistory2> mGlobalHistory;
     nsCOMPtr<nsIWebBrowserFind> mFind;
-    nsPoint                    mDefaultScrollbarPref; // persistent across doc loads
+    nsIntPoint                 mDefaultScrollbarPref; // persistent across doc loads
     // Reference to the SHEntry for this docshell until the page is destroyed.
     // Somebody give me better name
     nsCOMPtr<nsISHEntry>       mOSHE; 
diff --git a/docshell/base/nsIContentViewer.idl b/docshell/base/nsIContentViewer.idl
index aee96d4ba924..87ce75361be0 100644
--- a/docshell/base/nsIContentViewer.idl
+++ b/docshell/base/nsIContentViewer.idl
@@ -7,18 +7,18 @@ interface nsIPrintSettings;
 
 %{ C++
 class nsIWidget;
-struct nsRect;
+struct nsIntRect;
 %}
 
 [ptr] native nsIWidgetPtr(nsIWidget);
-[ref] native nsRectRef(nsRect);
+[ref] native nsIntRectRef(nsIntRect);
 
-[scriptable, uuid(05b290ac-d880-4900-bb1f-2211b5f8accc)]
+[scriptable, uuid(c9aba5da-7d8b-46a8-87cd-9ab7e16480b8)]
 interface nsIContentViewer : nsISupports
 {
 
   [noscript] void init(in nsIWidgetPtr aParentWidget,
-                       [const] in nsRectRef aBounds);
+                       [const] in nsIntRectRef aBounds);
 
   attribute nsISupports container;
 
@@ -55,8 +55,8 @@ interface nsIContentViewer : nsISupports
 
   attribute nsIDOMDocument DOMDocument;
 
-  [noscript] void getBounds(in nsRectRef aBounds);
-  [noscript] void setBounds([const] in nsRectRef aBounds);
+  [noscript] void getBounds(in nsIntRectRef aBounds);
+  [noscript] void setBounds([const] in nsIntRectRef aBounds);
 
   /**
    * The previous content viewer, which has been |close|d but not
diff --git a/docshell/shistory/public/nsISHEntry.idl b/docshell/shistory/public/nsISHEntry.idl
index 11bb8c6311a6..6235345c9eb2 100644
--- a/docshell/shistory/public/nsISHEntry.idl
+++ b/docshell/shistory/public/nsISHEntry.idl
@@ -51,14 +51,14 @@ interface nsIInputStream;
 interface nsIDocShellTreeItem;
 interface nsISupportsArray;
 %{C++
-struct nsRect;
+struct nsIntRect;
 class nsDocShellEditorData;
 %}
-[ref] native nsRect(nsRect);
+[ref] native nsIntRect(nsIntRect);
 [ptr] native nsDocShellEditorDataPtr(nsDocShellEditorData);
 
 
-[scriptable, uuid(c16fde76-3108-450e-8c8c-ae8286f286ed)]
+[scriptable, uuid(09fecea6-5453-43ba-bf91-3ff32618f037)]
 interface nsISHEntry : nsIHistoryEntry
 {
     /** URI for the document */
@@ -81,8 +81,8 @@ interface nsISHEntry : nsIHistoryEntry
      * root view's widget accordingly if this has changed when the presentation
      * is restored.
      */
-    [noscript] void getViewerBounds(in nsRect bounds);
-    [noscript] void setViewerBounds([const] in nsRect bounds);
+    [noscript] void getViewerBounds(in nsIntRect bounds);
+    [noscript] void setViewerBounds([const] in nsIntRect bounds);
 
     /**
      * Saved child docshells corresponding to contentViewer.  The child shells
diff --git a/docshell/shistory/src/nsSHEntry.cpp b/docshell/shistory/src/nsSHEntry.cpp
index 7d807bc48a1f..0da6e47897d4 100644
--- a/docshell/shistory/src/nsSHEntry.cpp
+++ b/docshell/shistory/src/nsSHEntry.cpp
@@ -536,14 +536,14 @@ nsSHEntry::GetWindowState(nsISupports **aState)
 }
 
 NS_IMETHODIMP
-nsSHEntry::SetViewerBounds(const nsRect &aBounds)
+nsSHEntry::SetViewerBounds(const nsIntRect &aBounds)
 {
   mViewerBounds = aBounds;
   return NS_OK;
 }
 
 NS_IMETHODIMP
-nsSHEntry::GetViewerBounds(nsRect &aBounds)
+nsSHEntry::GetViewerBounds(nsIntRect &aBounds)
 {
   aBounds = mViewerBounds;
   return NS_OK;
diff --git a/docshell/shistory/src/nsSHEntry.h b/docshell/shistory/src/nsSHEntry.h
index e87c6f4a99ff..3eebc2b6daea 100644
--- a/docshell/shistory/src/nsSHEntry.h
+++ b/docshell/shistory/src/nsSHEntry.h
@@ -110,7 +110,7 @@ private:
   nsCOMPtr<nsISupports>           mCacheKey;
   nsISHEntry *                    mParent;  // weak reference
   nsCOMPtr<nsISupports>           mWindowState;
-  nsRect                          mViewerBounds;
+  nsIntRect                       mViewerBounds;
   nsCOMArray<nsIDocShellTreeItem> mChildShells;
   nsCOMPtr<nsISupportsArray>      mRefreshURIList;
   nsCOMPtr<nsISupports>           mOwner;
diff --git a/editor/libeditor/base/nsEditor.cpp b/editor/libeditor/base/nsEditor.cpp
index a75cf269c325..20fcb5bf6306 100644
--- a/editor/libeditor/base/nsEditor.cpp
+++ b/editor/libeditor/base/nsEditor.cpp
@@ -1983,18 +1983,23 @@ nsEditor::QueryComposition(nsTextEventReply* aReply)
       // XXX_kin: END HACK! HACK! HACK!
 
       nsIView *view = nsnull;
+      nsRect rect;
       result =
         caretP->GetCaretCoordinates(nsCaret::eRenderingViewCoordinates,
                                     selection,
-                                    &(aReply->mCursorPosition),
+                                    &rect,
                                     &(aReply->mCursorIsCollapsed),
                                     &view);
+      aReply->mCursorPosition =
+        nsRect::ToOutsidePixels(rect,
+                                ps->GetPresContext()->AppUnitsPerDevPixel());
       if (NS_SUCCEEDED(result) && view)
         aReply->mReferenceWidget = view->GetWidget();
     }
   }
   return result;
 }
+
 NS_IMETHODIMP
 nsEditor::BeginComposition(nsTextEventReply* aReply)
 {
diff --git a/editor/libeditor/text/nsPlaintextEditor.cpp b/editor/libeditor/text/nsPlaintextEditor.cpp
index e42e84383844..8795b61068f0 100644
--- a/editor/libeditor/text/nsPlaintextEditor.cpp
+++ b/editor/libeditor/text/nsPlaintextEditor.cpp
@@ -1737,11 +1737,15 @@ nsPlaintextEditor::SetCompositionString(const nsAString& aCompositionString, nsI
   if (caretP)
   {
     nsIView *view = nsnull;
+    nsRect rect;
     result = caretP->GetCaretCoordinates(nsCaret::eRenderingViewCoordinates,
                                          selection,
-                                         &(aReply->mCursorPosition),
+                                         &rect,
                                          &(aReply->mCursorIsCollapsed),
                                          &view);
+    aReply->mCursorPosition =
+       nsRect::ToOutsidePixels(rect, 
+                               ps->GetPresContext()->AppUnitsPerDevPixel());
     NS_ASSERTION(NS_SUCCEEDED(result), "cannot get caret position");
     if (NS_SUCCEEDED(result) && view)
       aReply->mReferenceWidget = view->GetWidget();
diff --git a/embedding/browser/gtk/src/EmbedContextMenuInfo.cpp b/embedding/browser/gtk/src/EmbedContextMenuInfo.cpp
index 2bb6178a44b5..442488d47554 100644
--- a/embedding/browser/gtk/src/EmbedContextMenuInfo.cpp
+++ b/embedding/browser/gtk/src/EmbedContextMenuInfo.cpp
@@ -94,7 +94,7 @@ EmbedContextMenuInfo::EmbedContextMenuInfo(EmbedPrivate *aOwner) : mCtxFrameNum(
   mNSHHTMLElementSc = nsnull;
   mCtxEvent = nsnull;
   mEventNode = nsnull;
-  mFormRect = nsRect(0,0,0,0);
+  mFormRect = nsIntRect(0,0,0,0);
 }
 
 EmbedContextMenuInfo::~EmbedContextMenuInfo(void)
diff --git a/embedding/browser/gtk/src/EmbedContextMenuInfo.h b/embedding/browser/gtk/src/EmbedContextMenuInfo.h
index 0b1f69e3f4aa..f3b0d8902bdc 100644
--- a/embedding/browser/gtk/src/EmbedContextMenuInfo.h
+++ b/embedding/browser/gtk/src/EmbedContextMenuInfo.h
@@ -84,7 +84,7 @@ public:
   nsCOMPtr<nsIDOMNode>    mEventNode;
   nsCOMPtr<nsIDOMEventTarget> mEventTarget;
   nsCOMPtr<nsIDOMDocument>mCtxDocument;
-  nsRect               mFormRect;
+  nsIntRect               mFormRect;
   nsCOMPtr<nsIDOMWindow>  mCtxDomWindow;
   nsCOMPtr<nsIDOMEvent>   mCtxEvent;
   nsCOMPtr<nsIDOMNSHTMLElement> mNSHHTMLElement;
diff --git a/embedding/browser/webBrowser/nsDocShellTreeOwner.cpp b/embedding/browser/webBrowser/nsDocShellTreeOwner.cpp
index 331250930473..d42e82ec5f43 100644
--- a/embedding/browser/webBrowser/nsDocShellTreeOwner.cpp
+++ b/embedding/browser/webBrowser/nsDocShellTreeOwner.cpp
@@ -1482,8 +1482,8 @@ ChromeTooltipListener::sTooltipCallback(nsITimer *aTimer,
       if (textFound) {
         nsString tipText(tooltipText);
         self->CreateAutoHideTimer();
-        nsRect widgetDot(0, 0, 1, 1);
-        nsRect screenDot;
+        nsIntRect widgetDot(0, 0, 1, 1);
+        nsIntRect screenDot;
         widget->WidgetToScreen(widgetDot, screenDot);
         self->ShowTooltip (self->mMouseScreenX - screenDot.x,
                            self->mMouseScreenY - screenDot.y,
diff --git a/embedding/browser/webBrowser/nsWebBrowser.cpp b/embedding/browser/webBrowser/nsWebBrowser.cpp
index b31ae17489c1..262685a526fe 100644
--- a/embedding/browser/webBrowser/nsWebBrowser.cpp
+++ b/embedding/browser/webBrowser/nsWebBrowser.cpp
@@ -1129,7 +1129,7 @@ NS_IMETHODIMP nsWebBrowser::Create()
         mContentType == typeChromeWrapper)? eContentTypeUI: eContentTypeContent;
 
       widgetInit.mWindowType = eWindowType_child;
-      nsRect bounds(mInitInfo->x, mInitInfo->y, mInitInfo->cx, mInitInfo->cy);
+      nsIntRect bounds(mInitInfo->x, mInitInfo->y, mInitInfo->cx, mInitInfo->cy);
       
       mInternalWidget->SetClientData(static_cast<nsWebBrowser *>(this));
       mInternalWidget->Create(mParentNativeWindow, bounds, nsWebBrowser::HandleEvent,
@@ -1317,7 +1317,7 @@ NS_IMETHODIMP nsWebBrowser::GetPositionAndSize(PRInt32* aX, PRInt32* aY,
       {
       if(mInternalWidget)
          {
-         nsRect bounds;
+         nsIntRect bounds;
          NS_ENSURE_SUCCESS(mInternalWidget->GetBounds(bounds), NS_ERROR_FAILURE);
 
          if(aX)
diff --git a/embedding/components/printingui/src/win/nsPrintDialogUtil.cpp b/embedding/components/printingui/src/win/nsPrintDialogUtil.cpp
index f2cb197490a3..7884684ee4eb 100644
--- a/embedding/components/printingui/src/win/nsPrintDialogUtil.cpp
+++ b/embedding/components/printingui/src/win/nsPrintDialogUtil.cpp
@@ -513,7 +513,7 @@ static HWND CreateControl(LPCTSTR          aType,
                           HWND             aHdlg, 
                           int              aId, 
                           const nsAString& aStr, 
-                          const nsRect&    aRect)
+                          const nsIntRect& aRect)
 {
   nsCAutoString str;
   if (NS_FAILED(NS_CopyUnicodeToNative(aStr, str)))
@@ -541,7 +541,7 @@ static HWND CreateRadioBtn(HINSTANCE        aHInst,
                            HWND             aHdlg, 
                            int              aId, 
                            const char*      aStr, 
-                           const nsRect&    aRect)
+                           const nsIntRect& aRect)
 {
   nsString cStr;
   cStr.AssignWithConversion(aStr);
@@ -554,7 +554,7 @@ static HWND CreateGroupBox(HINSTANCE        aHInst,
                            HWND             aHdlg, 
                            int              aId, 
                            const nsAString& aStr, 
-                           const nsRect&    aRect)
+                           const nsIntRect& aRect)
 {
   return CreateControl("BUTTON", BS_GROUPBOX, aHInst, aHdlg, aId, aStr, aRect);
 }
@@ -665,7 +665,7 @@ static UINT CALLBACK PrintHookProc(HWND hdlg, UINT uiMsg, WPARAM wParam, LPARAM
     int y         = top+(rad1Rect.top-dlgRect.top);     // starting pos of first radio
     int rbWidth   = dlgRect.right - rad1Rect.left - 5;  // measure from rb left to the edge of the groupbox
                                                         // (5 is arbitrary)
-    nsRect rect;
+    nsIntRect rect;
 
     // Create and position the radio buttons
     //
diff --git a/gfx/public/nsITheme.h b/gfx/public/nsITheme.h
index cf3ca7448712..d2cc76ab1e46 100644
--- a/gfx/public/nsITheme.h
+++ b/gfx/public/nsITheme.h
@@ -46,9 +46,9 @@
 #include "nsColor.h"
 
 struct nsRect;
-struct nsSize;
+struct nsIntSize;
 struct nsFont;
-struct nsMargin;
+struct nsIntMargin;
 class nsPresContext;
 class nsIRenderingContext;
 class nsIDeviceContext;
@@ -57,9 +57,9 @@ class nsIContent;
 class nsIAtom;
 
 // IID for the nsITheme interface
-// {df8baf21-5ea7-49eb-a2bc-f2fd4a9fd896}
+// {887e8902-db6b-41b4-8481-a80f49c5a93a}
 #define NS_ITHEME_IID     \
-{ 0xdf8baf21, 0x5ea7, 0x49eb, { 0xa2, 0xbc, 0xf2, 0xfd, 0x4a, 0x9f, 0xd8, 0x96 } }
+{ 0x887e8902, 0xdb6b, 0x41b4, { 0x84, 0x81, 0xa8, 0x0f, 0x49, 0xc5, 0xa9, 0x3a } }
 
 // {D930E29B-6909-44e5-AB4B-AF10D6923705}
 #define NS_THEMERENDERER_CID \
@@ -91,7 +91,7 @@ public:
   NS_IMETHOD GetWidgetBorder(nsIDeviceContext* aContext, 
                              nsIFrame* aFrame,
                              PRUint8 aWidgetType,
-                             nsMargin* aResult)=0;
+                             nsIntMargin* aResult)=0;
 
   /**
    * This method can return PR_FALSE to indicate that the CSS padding
@@ -105,7 +105,7 @@ public:
   virtual PRBool GetWidgetPadding(nsIDeviceContext* aContext,
                                   nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsMargin* aResult) = 0;
+                                  nsIntMargin* aResult) = 0;
 
   /**
    * On entry, *aResult is positioned at 0,0 and sized to the new size
@@ -130,7 +130,7 @@ public:
   NS_IMETHOD GetMinimumWidgetSize(nsIRenderingContext* aContext,
                                   nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsSize* aResult,
+                                  nsIntSize* aResult,
                                   PRBool* aIsOverridable)=0;
 
   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, PRUint8 aWidgetType, 
diff --git a/gfx/public/nsMargin.h b/gfx/public/nsMargin.h
index f939c47e8a22..e9fee87263d3 100644
--- a/gfx/public/nsMargin.h
+++ b/gfx/public/nsMargin.h
@@ -105,7 +105,6 @@ struct nsMargin {
                                                  return *this;}
 };
 
-#ifdef NS_COORD_IS_FLOAT
 struct nsIntMargin {
   PRInt32 top, right, bottom, left;
 
@@ -115,9 +114,25 @@ struct nsIntMargin {
   nsIntMargin(PRInt32 aLeft,  PRInt32 aTop,
               PRInt32 aRight, PRInt32 aBottom) {left = aLeft; top = aTop;
                                                 right = aRight; bottom = aBottom;}
+  void SizeTo(PRInt32 aLeft,  PRInt32 aTop,
+              PRInt32 aRight, PRInt32 aBottom) {left = aLeft; top = aTop;
+                                                right = aRight; bottom = aBottom;}
+  PRInt32& side(PRUint8 aSide) {
+    NS_PRECONDITION(aSide <= NS_SIDE_LEFT, "Out of range side");
+    return *(&top + aSide);
+  }    
+
+  PRInt32 side(PRUint8 aSide) const {
+    NS_PRECONDITION(aSide <= NS_SIDE_LEFT, "Out of range side");
+    return *(&top + aSide);
+  }    
+  PRInt32 LeftRight() const { return left + right; }
+  PRInt32 TopBottom() const { return top + bottom; }
+
+  nsIntMargin operator+(const nsIntMargin& aMargin) const {
+    return nsIntMargin(left + aMargin.left, top + aMargin.top,
+                    right + aMargin.right, bottom + aMargin.bottom);
+  }
 };
-#else
-typedef nsMargin nsIntMargin;
-#endif
 
 #endif /* NSMARGIN_H */
diff --git a/gfx/public/nsPoint.h b/gfx/public/nsPoint.h
index cf2977500123..1c59ab1ec0fe 100644
--- a/gfx/public/nsPoint.h
+++ b/gfx/public/nsPoint.h
@@ -81,7 +81,6 @@ struct nsPoint {
   }
 };
 
-#ifdef NS_COORD_IS_FLOAT
 struct nsIntPoint {
   PRInt32 x, y;
 
@@ -90,50 +89,29 @@ struct nsIntPoint {
   nsIntPoint(const nsIntPoint& aPoint) { x = aPoint.x; y = aPoint.y;}
   nsIntPoint(PRInt32 aX, PRInt32 aY) { x = aX; y = aY;}
 
-  void MoveTo(PRInt32 aX, PRInt32 aY) {x = aX; y = aY;}
-};
-
-typedef nsPoint nsFloatPoint;
-#else
-typedef nsPoint nsIntPoint;
-
-struct nsFloatPoint {
-  float x, y;
-
-  // Constructors
-  nsFloatPoint() {}
-  nsFloatPoint(const nsFloatPoint& aPoint) {x = aPoint.x; y = aPoint.y;}
-  nsFloatPoint(float aX, float aY) {x = aX; y = aY;}
-
-  void MoveTo(float aX, float aY) {x = aX; y = aY;}
-  void MoveTo(nscoord aX, nscoord aY) {x = (float)aX; y = (float)aY;}
-  void MoveBy(float aDx, float aDy) {x += aDx; y += aDy;}
-
-  // Overloaded operators. Note that '=' isn't defined so we'll get the
-  // compiler generated default assignment operator
-  PRBool   operator==(const nsFloatPoint& aPoint) const {
+  PRBool   operator==(const nsIntPoint& aPoint) const {
     return (PRBool) ((x == aPoint.x) && (y == aPoint.y));
   }
-  PRBool   operator!=(const nsFloatPoint& aPoint) const {
+  PRBool   operator!=(const nsIntPoint& aPoint) const {
     return (PRBool) ((x != aPoint.x) || (y != aPoint.y));
   }
-  nsFloatPoint operator+(const nsFloatPoint& aPoint) const {
-    return nsFloatPoint(x + aPoint.x, y + aPoint.y);
+  nsIntPoint operator+(const nsIntPoint& aPoint) const {
+    return nsIntPoint(x + aPoint.x, y + aPoint.y);
   }
-  nsFloatPoint operator-(const nsFloatPoint& aPoint) const {
-    return nsFloatPoint(x - aPoint.x, y - aPoint.y);
+  nsIntPoint operator-(const nsIntPoint& aPoint) const {
+    return nsIntPoint(x - aPoint.x, y - aPoint.y);
   }
-  nsFloatPoint& operator+=(const nsFloatPoint& aPoint) {
+  nsIntPoint& operator+=(const nsIntPoint& aPoint) {
     x += aPoint.x;
     y += aPoint.y;
     return *this;
   }
-  nsFloatPoint& operator-=(const nsFloatPoint& aPoint) {
+  nsIntPoint& operator-=(const nsIntPoint& aPoint) {
     x -= aPoint.x;
     y -= aPoint.y;
     return *this;
   }
+  void MoveTo(PRInt32 aX, PRInt32 aY) {x = aX; y = aY;}
 };
-#endif // !NS_COORD_IS_FLOAT
 
 #endif /* NSPOINT_H */
diff --git a/gfx/public/nsRect.h b/gfx/public/nsRect.h
index cf96e10f9278..b50f6a8616c1 100644
--- a/gfx/public/nsRect.h
+++ b/gfx/public/nsRect.h
@@ -47,6 +47,8 @@
 #include "gfxCore.h"
 #include "nsTraceRefcnt.h"
 
+struct nsIntRect;
+
 struct NS_GFX nsRect {
   nscoord x, y;
   nscoord width, height;
@@ -168,26 +170,6 @@ struct NS_GFX nsRect {
   nsRect& operator+=(const nsPoint& aPoint) {x += aPoint.x; y += aPoint.y; return *this;}
   nsRect& operator-=(const nsPoint& aPoint) {x -= aPoint.x; y -= aPoint.y; return *this;}
 
-  nsRect& operator*=(const float aScale) {x = NSToCoordRound(x * aScale); 
-                                          y = NSToCoordRound(y * aScale); 
-                                          width = NSToCoordRound(width * aScale); 
-                                          height = NSToCoordRound(height * aScale); 
-                                          return *this;}
-
-  // Scale by aScale, converting coordinates to integers so that the result
-  // is the smallest integer-coordinate rectangle containing the unrounded result
-  nsRect& ScaleRoundOut(float aScale);
-  // Scale by the inverse of aScale, converting coordinates to integers so that the result
-  // is the smallest integer-coordinate rectangle containing the unrounded result.
-  // More accurate than ScaleRoundOut(1.0/aScale).
-  nsRect& ScaleRoundOutInverse(float aScale);
-  // Scale by aScale, converting coordinates to integers so that the result
-  // is the larges integer-coordinate rectangle contained in the unrounded result
-  nsRect& ScaleRoundIn(float aScale);
-  // Scale by the inverse of aScale, converting coordinates to integers so that
-  // the result contains the same pixel centers as the unrounded result
-  nsRect& ScaleRoundPreservingCentersInverse(float aScale);
-
   // Helpers for accessing the vertices
   nsPoint TopLeft() const { return nsPoint(x, y); }
   nsPoint TopRight() const { return nsPoint(XMost(), y); }
@@ -199,9 +181,14 @@ struct NS_GFX nsRect {
   // Helper methods for computing the extents
   nscoord XMost() const {return x + width;}
   nscoord YMost() const {return y + height;}
+
+  inline nsRect ScaleRoundOutInverse(float aFactor);
+
+  static inline nsIntRect ToNearestPixels(const nsRect &aRect, nscoord aAppUnitsPerPixel);
+  static inline nsIntRect ToOutsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel);
+  static inline nsIntRect ToInsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel);
 };
 
-#ifdef NS_COORD_IS_FLOAT
 struct NS_GFX nsIntRect {
   PRInt32 x, y;
   PRInt32 width, height;
@@ -209,6 +196,10 @@ struct NS_GFX nsIntRect {
   // Constructors
   nsIntRect() : x(0), y(0), width(0), height(0) {}
   nsIntRect(const nsIntRect& aRect) {*this = aRect;}
+  nsIntRect(const nsIntPoint& aOrigin, const nsIntSize &aSize) {
+    x = aOrigin.x; y = aOrigin.y;
+    width = aSize.width; height = aSize.height;
+  }
   nsIntRect(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRInt32 aHeight) {
     x = aX; y = aY; width = aWidth; height = aHeight;
   }
@@ -218,11 +209,74 @@ struct NS_GFX nsIntRect {
   PRBool IsEmpty() const {
     return (PRBool) ((height <= 0) || (width <= 0));
   }
+  void Empty() {width = height = 0;}
+
+  // Inflate the rect by the specified width/height or margin
+  void Inflate(PRInt32 aDx, PRInt32 aDy) {
+    x -= aDx;
+    y -= aDy;
+    width += aDx*2;
+    height += aDy*2;
+  }
+  void Inflate(const nsIntMargin &aMargin) {
+    x -= aMargin.left;
+    y -= aMargin.top;
+    width += aMargin.left + aMargin.right;
+    height += aMargin.top + aMargin.bottom;
+  }
+
+  // Overloaded operators. Note that '=' isn't defined so we'll get the
+  // compiler generated default assignment operator.
+  PRBool operator==(const nsIntRect& aRect) const {
+    return (PRBool) ((IsEmpty() && aRect.IsEmpty()) ||
+                     ((x == aRect.x) && (y == aRect.y) &&
+                      (width == aRect.width) && (height == aRect.height)));
+  }
+  PRBool  operator!=(const nsIntRect& aRect) const {
+    return (PRBool) !operator==(aRect);
+  }
+
+  nsIntRect  operator+(const nsIntPoint& aPoint) const {
+    return nsIntRect(x + aPoint.x, y + aPoint.y, width, height);
+  }
+  nsIntRect  operator-(const nsIntPoint& aPoint) const {
+    return nsIntRect(x - aPoint.x, y - aPoint.y, width, height);
+  }
+  nsIntRect& operator+=(const nsIntPoint& aPoint) {x += aPoint.x; y += aPoint.y; return *this;}
+  nsIntRect& operator-=(const nsIntPoint& aPoint) {x -= aPoint.x; y -= aPoint.y; return *this;}
 
   void SetRect(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRInt32 aHeight) {
     x = aX; y = aY; width = aWidth; height = aHeight;
   }
 
+  void MoveTo(PRInt32 aX, PRInt32 aY) {x = aX; y = aY;}
+  void MoveTo(const nsIntPoint& aPoint) {x = aPoint.x; y = aPoint.y;}
+  void MoveBy(PRInt32 aDx, PRInt32 aDy) {x += aDx; y += aDy;}
+  void MoveBy(const nsIntPoint& aPoint) {x += aPoint.x; y += aPoint.y;}
+  void SizeTo(PRInt32 aWidth, PRInt32 aHeight) {width = aWidth; height = aHeight;}
+  void SizeTo(const nsIntSize& aSize) {SizeTo(aSize.width, aSize.height);}
+  void SizeBy(PRInt32 aDeltaWidth, PRInt32 aDeltaHeight) {width += aDeltaWidth;
+                                                          height += aDeltaHeight;}
+
+  PRBool Contains(const nsIntRect& aRect) const
+  {
+    return (PRBool) ((aRect.x >= x) && (aRect.y >= y) &&
+                     (aRect.XMost() <= XMost()) && (aRect.YMost() <= YMost()));
+  }
+  PRBool Contains(PRInt32 aX, PRInt32 aY) const
+  {
+    return (PRBool) ((aX >= x) && (aY >= y) &&
+                     (aX < XMost()) && (aY < YMost()));
+  }
+  PRBool Contains(const nsIntPoint& aPoint) const { return Contains(aPoint.x, aPoint.y); }
+
+  // Intersection. Returns TRUE if the receiver overlaps aRect and
+  // FALSE otherwise
+  PRBool Intersects(const nsIntRect& aRect) const {
+    return (PRBool) ((x < aRect.XMost()) && (y < aRect.YMost()) &&
+                     (aRect.x < XMost()) && (aRect.y < YMost()));
+  }
+  
   // Computes the area in which aRect1 and aRect2 overlap, and fills 'this' with
   // the result. Returns FALSE if the rectangles don't intersect, and sets 'this'
   // rect to be an empty rect.
@@ -237,13 +291,86 @@ struct NS_GFX nsIntRect {
   // 'this' can be the same object as either aRect1 or aRect2
   PRBool UnionRect(const nsIntRect& aRect1, const nsIntRect& aRect2);
 
+  // Helpers for accessing the vertices
+  nsIntPoint TopLeft() const { return nsIntPoint(x, y); }
+  nsIntPoint TopRight() const { return nsIntPoint(XMost(), y); }
+  nsIntPoint BottomLeft() const { return nsIntPoint(x, YMost()); }
+  nsIntPoint BottomRight() const { return nsIntPoint(XMost(), YMost()); }
+
+  nsIntSize Size() const { return nsIntSize(width, height); }
+
   // Helper methods for computing the extents
   PRInt32 XMost() const {return x + width;}
   PRInt32 YMost() const {return y + height;}
+
+  static inline nsRect ToAppUnits(const nsIntRect &aRect, nscoord aAppUnitsPerPixel);
 };
-#else
-typedef nsRect nsIntRect;
-#endif
+
+inline nsRect
+nsRect::ScaleRoundOutInverse(float aFactor)
+{
+  nsRect rect;
+  rect.x = NSToIntFloor(x / aFactor);
+  rect.y = NSToIntFloor(y / aFactor);
+  rect.width = NSToIntCeil(XMost() / aFactor) - rect.x;
+  rect.height = NSToIntCeil(YMost() / aFactor) - rect.y;
+  return rect;
+}
+
+/* 
+ * App Unit/Pixel conversions
+ */
+// scale the rect but round to preserve centers
+inline nsIntRect
+nsRect::ToNearestPixels(const nsRect &aRect, nscoord aAppUnitsPerPixel)
+{
+  nsIntRect rect;  
+  rect.x = NSToIntRound(NSAppUnitsToFloatPixels(aRect.x, aAppUnitsPerPixel));
+  rect.y = NSToIntRound(NSAppUnitsToFloatPixels(aRect.y, aAppUnitsPerPixel));
+  rect.width  = NSToIntRound(NSAppUnitsToFloatPixels(aRect.XMost(),
+                             aAppUnitsPerPixel)) - rect.x;
+  rect.height = NSToIntRound(NSAppUnitsToFloatPixels(aRect.YMost(),
+                             aAppUnitsPerPixel)) - rect.y;
+  return rect;
+}
+
+// scale the rect but round to smallest containing rect
+inline nsIntRect
+nsRect::ToOutsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel)
+{
+  nsIntRect rect;  
+  rect.x = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.x, aAppUnitsPerPixel));
+  rect.y = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.y, aAppUnitsPerPixel));
+  rect.width  = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.XMost(),
+                            aAppUnitsPerPixel)) - rect.x;
+  rect.height = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.YMost(),
+                            aAppUnitsPerPixel)) - rect.y;
+  return rect;
+}
+
+// scale the rect but round to largest contained rect
+inline nsIntRect
+nsRect::ToInsidePixels(const nsRect &aRect, nscoord aAppUnitsPerPixel)
+{
+  nsIntRect rect;  
+  rect.x = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.x, aAppUnitsPerPixel));
+  rect.y = NSToIntCeil(NSAppUnitsToFloatPixels(aRect.y, aAppUnitsPerPixel));
+  rect.width  = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.XMost(),
+                             aAppUnitsPerPixel)) - rect.x;
+  rect.height = NSToIntFloor(NSAppUnitsToFloatPixels(aRect.YMost(),
+                             aAppUnitsPerPixel)) - rect.y;
+  return rect;
+}
+
+// app units are integer multiples of pixels, so no rounding needed
+inline nsRect
+nsIntRect::ToAppUnits(const nsIntRect &aRect, nscoord aAppUnitsPerPixel)
+{
+  return nsRect(NSIntPixelsToAppUnits(aRect.x, aAppUnitsPerPixel),
+                NSIntPixelsToAppUnits(aRect.y, aAppUnitsPerPixel),
+                NSIntPixelsToAppUnits(aRect.width, aAppUnitsPerPixel),
+                NSIntPixelsToAppUnits(aRect.height, aAppUnitsPerPixel));
+}
 
 #ifdef DEBUG
 // Diagnostics
diff --git a/gfx/public/nsSize.h b/gfx/public/nsSize.h
index 22b5daf6937c..53790b3fbc35 100644
--- a/gfx/public/nsSize.h
+++ b/gfx/public/nsSize.h
@@ -71,7 +71,6 @@ struct nsSize {
                                            return *this;}
 };
 
-#ifdef NS_COORD_IS_FLOAT
 struct nsIntSize {
   PRInt32 width, height;
 
@@ -79,10 +78,16 @@ struct nsIntSize {
   nsIntSize(const nsIntSize& aSize) {width = aSize.width; height = aSize.height;}
   nsIntSize(PRInt32 aWidth, PRInt32 aHeight) {width = aWidth; height = aHeight;}
 
+  // Overloaded operators. Note that '=' isn't defined so we'll get the
+  // compiler generated default assignment operator
+  PRBool  operator==(const nsIntSize& aSize) const {
+    return (PRBool) ((width == aSize.width) && (height == aSize.height));
+  }
+  PRBool  operator!=(const nsIntSize& aSize) const {
+    return (PRBool) ((width != aSize.width) || (height != aSize.height));
+  }
+
   void SizeTo(PRInt32 aWidth, PRInt32 aHeight) {width = aWidth; height = aHeight;}
 };
-#else
-typedef nsSize nsIntSize;
-#endif
 
 #endif /* NSSIZE_H */
diff --git a/gfx/src/nsRect.cpp b/gfx/src/nsRect.cpp
index e7ba395672ca..25dcd34f07ec 100644
--- a/gfx/src/nsRect.cpp
+++ b/gfx/src/nsRect.cpp
@@ -173,52 +173,6 @@ void nsRect::Deflate(const nsMargin &aMargin)
   height = PR_MAX(0, height - aMargin.TopBottom());
 }
 
-// scale the rect but round to smallest containing rect
-nsRect& nsRect::ScaleRoundOut(float aScale) 
-{
-  nscoord right = NSToCoordCeil(float(XMost()) * aScale);
-  nscoord bottom = NSToCoordCeil(float(YMost()) * aScale);
-  x = NSToCoordFloor(float(x) * aScale);
-  y = NSToCoordFloor(float(y) * aScale);
-  width = (right - x);
-  height = (bottom - y);
-  return *this;
-}
-
-nsRect& nsRect::ScaleRoundOutInverse(float aScale) 
-{
-  nscoord right = NSToCoordCeil(float(XMost()) / aScale);
-  nscoord bottom = NSToCoordCeil(float(YMost()) / aScale);
-  x = NSToCoordFloor(float(x) / aScale);
-  y = NSToCoordFloor(float(y) / aScale);
-  width = (right - x);
-  height = (bottom - y);
-  return *this;
-}
-
-// scale the rect but round to largest contained rect
-nsRect& nsRect::ScaleRoundIn(float aScale) 
-{
-  nscoord right = NSToCoordFloor(float(XMost()) * aScale);
-  nscoord bottom = NSToCoordFloor(float(YMost()) * aScale);
-  x = NSToCoordCeil(float(x) * aScale);
-  y = NSToCoordCeil(float(y) * aScale);
-  width = (right - x);
-  height = (bottom - y);
-  return *this;
-}
-
-nsRect& nsRect::ScaleRoundPreservingCentersInverse(float aScale)
-{
-  nscoord right = NSToCoordRound(float(XMost()) / aScale);
-  nscoord bottom = NSToCoordRound(float(YMost()) / aScale);
-  x = NSToCoordRound(float(x) / aScale);
-  y = NSToCoordRound(float(y) / aScale);
-  width = (right - x);
-  height = (bottom - y);
-  return *this;
-}
-
 #ifdef DEBUG
 // Diagnostics
 
@@ -244,7 +198,8 @@ FILE* operator<<(FILE* out, const nsRect& rect)
   return out;
 }
 
-#ifdef NS_COORD_IS_FLOAT
+#endif // DEBUG
+
 // Computes the area in which aRect1 and aRect2 overlap and fills 'this' with
 // the result. Returns FALSE if the rectangles don't intersect.
 PRBool nsIntRect::IntersectRect(const nsIntRect &aRect1, const nsIntRect &aRect2)
@@ -314,6 +269,4 @@ PRBool nsIntRect::UnionRect(const nsIntRect &aRect1, const nsIntRect &aRect2)
 
   return result;
 }
-#endif
 
-#endif // DEBUG
diff --git a/gfx/src/thebes/nsThebesImage.cpp b/gfx/src/thebes/nsThebesImage.cpp
index 4081d8993e31..0e099c5d43f1 100644
--- a/gfx/src/thebes/nsThebesImage.cpp
+++ b/gfx/src/thebes/nsThebesImage.cpp
@@ -220,7 +220,7 @@ nsThebesImage::GetAlphaLineStride()
 }
 
 nsresult
-nsThebesImage::ImageUpdated(nsIDeviceContext *aContext, PRUint8 aFlags, nsRect *aUpdateRect)
+nsThebesImage::ImageUpdated(nsIDeviceContext *aContext, PRUint8 aFlags, nsIntRect *aUpdateRect)
 {
     // Check to see if we are running OOM
     nsCOMPtr<nsIMemory> mem;
@@ -245,7 +245,7 @@ PRBool
 nsThebesImage::GetIsImageComplete()
 {
     if (!mImageComplete)
-        mImageComplete = (mDecoded == nsRect(0, 0, mWidth, mHeight));
+        mImageComplete = (mDecoded == nsIntRect(0, 0, mWidth, mHeight));
     return mImageComplete;
 }
 
diff --git a/gfx/src/thebes/nsThebesImage.h b/gfx/src/thebes/nsThebesImage.h
index b7840a51d71b..5620b6fb0b6a 100644
--- a/gfx/src/thebes/nsThebesImage.h
+++ b/gfx/src/thebes/nsThebesImage.h
@@ -71,7 +71,7 @@ public:
     virtual PRUint8 *GetAlphaBits();
     virtual PRInt32 GetAlphaLineStride();
     virtual PRBool GetIsImageComplete();
-    virtual nsresult ImageUpdated(nsIDeviceContext *aContext, PRUint8 aFlags, nsRect *aUpdateRect);
+    virtual nsresult ImageUpdated(nsIDeviceContext *aContext, PRUint8 aFlags, nsIntRect *aUpdateRect);
     virtual nsresult Optimize(nsIDeviceContext* aContext);
     virtual nsColorMap *GetColorMap();
 
@@ -159,7 +159,7 @@ protected:
     PRInt32 mWidth;
     PRInt32 mHeight;
     PRInt32 mStride;
-    nsRect mDecoded;
+    nsIntRect mDecoded;
     PRPackedBool mImageComplete;
     PRPackedBool mSinglePixel;
     PRPackedBool mFormatChanged;
diff --git a/gfx/src/thebes/nsThebesRenderingContext.cpp b/gfx/src/thebes/nsThebesRenderingContext.cpp
index 28eac5509444..d1aba112e436 100644
--- a/gfx/src/thebes/nsThebesRenderingContext.cpp
+++ b/gfx/src/thebes/nsThebesRenderingContext.cpp
@@ -780,7 +780,7 @@ nsThebesRenderingContext::DrawTile(imgIContainer *aImage,
     aImage->GetCurrentFrame(getter_AddRefs(imgFrame));
     if (!imgFrame) return NS_ERROR_FAILURE;
 
-    nsRect imgFrameRect;
+    nsIntRect imgFrameRect;
     imgFrame->GetRect(imgFrameRect);
 
     nsCOMPtr<nsIImage> img(do_GetInterface(imgFrame));
diff --git a/layout/base/nsCSSRendering.cpp b/layout/base/nsCSSRendering.cpp
index 80275f59fc44..91c788deca80 100644
--- a/layout/base/nsCSSRendering.cpp
+++ b/layout/base/nsCSSRendering.cpp
@@ -1582,12 +1582,13 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
   nsCOMPtr<imgIContainer> image;
   req->GetImage(getter_AddRefs(image));
 
-  nsSize imageSize;
-  image->GetWidth(&imageSize.width);
-  image->GetHeight(&imageSize.height);
+  nsIntSize imageIntSize;
+  image->GetWidth(&imageIntSize.width);
+  image->GetHeight(&imageIntSize.height);
 
-  imageSize.width = nsPresContext::CSSPixelsToAppUnits(imageSize.width);
-  imageSize.height = nsPresContext::CSSPixelsToAppUnits(imageSize.height);
+  nsSize imageSize;
+  imageSize.width = nsPresContext::CSSPixelsToAppUnits(imageIntSize.width);
+  imageSize.height = nsPresContext::CSSPixelsToAppUnits(imageIntSize.height);
 
   req = nsnull;
 
@@ -1659,10 +1660,10 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
           gfxImgFrame->GetNeedsBackground(&needBackgroundColor);
 
           /* check for tiling of a image where frame smaller than container */
-          nsSize iSize;
+          nsIntSize iSize;
           image->GetWidth(&iSize.width);
           image->GetHeight(&iSize.height);
-          nsRect iframeRect;
+          nsIntRect iframeRect;
           gfxImgFrame->GetRect(iframeRect);
           if (iSize.width != iframeRect.width ||
               iSize.height != iframeRect.height) {
@@ -1968,9 +1969,9 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
     } else {
       // Note that the subimage is in tile space so it may cover
       // multiple tiles of the image.
-      subimageRect.ScaleRoundOutInverse(nsIDeviceContext::AppUnitsPerCSSPixel());
+      nsIntRect subimagePxRect(nsRect::ToOutsidePixels(subimageRect, nsIDeviceContext::AppUnitsPerCSSPixel()));
       aRenderingContext.DrawTile(image, absTileRect.x, absTileRect.y,
-              &drawRect, &subimageRect);
+              &drawRect, &subimagePxRect);
     }
   }
 
diff --git a/layout/base/nsDocumentViewer.cpp b/layout/base/nsDocumentViewer.cpp
index f0a8b1080834..f0e804496ad3 100644
--- a/layout/base/nsDocumentViewer.cpp
+++ b/layout/base/nsDocumentViewer.cpp
@@ -368,7 +368,7 @@ private:
    */
   nsresult InitInternal(nsIWidget* aParentWidget,
                         nsISupports *aState,
-                        const nsRect& aBounds,
+                        const nsIntRect& aBounds,
                         PRBool aDoCreation,
                         PRBool aInPrintPreview,
                         PRBool aNeedMakeCX = PR_TRUE);
@@ -666,7 +666,7 @@ DocumentViewerImpl::GetContainer(nsISupports** aResult)
 
 NS_IMETHODIMP
 DocumentViewerImpl::Init(nsIWidget* aParentWidget,
-                         const nsRect& aBounds)
+                         const nsIntRect& aBounds)
 {
   nsresult rv = CreateDeviceContext(aParentWidget);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -709,7 +709,7 @@ DocumentViewerImpl::InitPresentationStuff(PRBool aDoInitialReflow, PRBool aReena
   mPresShell->BeginObservingDocument();
 
   // Initialize our view manager
-  nsRect bounds;
+  nsIntRect bounds;
   mWindow->GetBounds(bounds);
 
   nscoord width = mPresContext->DeviceContext()->UnscaledAppUnitsPerDevPixel() * bounds.width;
@@ -805,7 +805,7 @@ DocumentViewerImpl::InitPresentationStuff(PRBool aDoInitialReflow, PRBool aReena
 nsresult
 DocumentViewerImpl::InitInternal(nsIWidget* aParentWidget,
                                  nsISupports *aState,
-                                 const nsRect& aBounds,
+                                 const nsIntRect& aBounds,
                                  PRBool aDoCreation,
                                  PRBool aInPrintPreview,
                                  PRBool aNeedMakeCX /*= PR_TRUE*/)
@@ -1247,7 +1247,7 @@ DocumentViewerImpl::Open(nsISupports *aState, nsISHEntry *aSHEntry)
   if (!container)
     return NS_ERROR_NOT_AVAILABLE;
 
-  nsRect bounds;
+  nsIntRect bounds;
   mWindow->GetBounds(bounds);
 
   nsresult rv = InitInternal(mParentWidget, aState, bounds, PR_FALSE, PR_FALSE);
@@ -1738,7 +1738,7 @@ DocumentViewerImpl::GetPresContext(nsPresContext** aResult)
 }
 
 NS_IMETHODIMP
-DocumentViewerImpl::GetBounds(nsRect& aResult)
+DocumentViewerImpl::GetBounds(nsIntRect& aResult)
 {
   NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
   NS_PRECONDITION(mWindow, "null window");
@@ -1793,7 +1793,7 @@ DocumentViewerImpl::SetPreviousViewer(nsIContentViewer* aViewer)
 }
 
 NS_IMETHODIMP
-DocumentViewerImpl::SetBounds(const nsRect& aBounds)
+DocumentViewerImpl::SetBounds(const nsIntRect& aBounds)
 {
   NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);
 
@@ -1900,7 +1900,7 @@ DocumentViewerImpl::Show(void)
       return rv;
     }
 
-    nsRect tbounds;
+    nsIntRect tbounds;
     mParentWidget->GetBounds(tbounds);
 
     rv = MakeWindow(nsSize(mPresContext->DevPixelsToAppUnits(tbounds.width),
@@ -4088,7 +4088,7 @@ NS_IMETHODIMP DocumentViewerImpl::SetPageMode(PRBool aPageMode, nsIPrintSettings
   // reftests that require a paginated context
   mIsPageMode = aPageMode;
   // Get the current size of what is being viewed
-  nsRect bounds;
+  nsIntRect bounds;
   mWindow->GetBounds(bounds);
 
   if (mPresShell) {
diff --git a/layout/base/nsIPresShell.h b/layout/base/nsIPresShell.h
index af3b5723289e..fdec63d23d62 100644
--- a/layout/base/nsIPresShell.h
+++ b/layout/base/nsIPresShell.h
@@ -102,11 +102,10 @@ class gfxContext;
 typedef short SelectionType;
 typedef PRUint32 nsFrameState;
 
-
-// 134e504f-4fd1-4590-9f5d-899afee63d0f
+// b86c23c5-602d-4ca6-a968-379b244fed9e
 #define NS_IPRESSHELL_IID \
-{ 0x134e504f, 0x4fd1, 0x4590, \
-  { 0x9f, 0x5d, 0x89, 0x9a, 0xfe, 0xe6, 0x3d, 0x0f } }
+{ 0xb86c23c5, 0x602d, 0x4ca6, \
+  { 0xa9, 0x68, 0x37, 0x9b, 0x24, 0x4f, 0xed, 0x9e } }
 
 // Constants for ScrollContentIntoView() function
 #define NS_PRESSHELL_SCROLL_TOP      0
@@ -739,8 +738,8 @@ public:
    */
   virtual already_AddRefed<gfxASurface> RenderNode(nsIDOMNode* aNode,
                                                    nsIRegion* aRegion,
-                                                   nsPoint& aPoint,
-                                                   nsRect* aScreenRect) = 0;
+                                                   nsIntPoint& aPoint,
+                                                   nsIntRect* aScreenRect) = 0;
 
   /*
    * Renders a selection to a surface and returns it. This method is primarily
@@ -758,8 +757,8 @@ public:
    * as the position can be determined from the displayed frames.
    */
   virtual already_AddRefed<gfxASurface> RenderSelection(nsISelection* aSelection,
-                                                        nsPoint& aPoint,
-                                                        nsRect* aScreenRect) = 0;
+                                                        nsIntPoint& aPoint,
+                                                        nsIntRect* aScreenRect) = 0;
 
   void AddWeakFrame(nsWeakFrame* aWeakFrame);
   void RemoveWeakFrame(nsWeakFrame* aWeakFrame);
diff --git a/layout/base/nsImageLoader.cpp b/layout/base/nsImageLoader.cpp
index f917dbb115c2..cc3be8faa7ed 100644
--- a/layout/base/nsImageLoader.cpp
+++ b/layout/base/nsImageLoader.cpp
@@ -184,7 +184,7 @@ NS_IMETHODIMP nsImageLoader::OnStopFrame(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsImageLoader::FrameChanged(imgIContainer *aContainer,
                                           gfxIImageFrame *newframe,
-                                          nsRect * dirtyRect)
+                                          nsIntRect *dirtyRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
@@ -194,12 +194,7 @@ NS_IMETHODIMP nsImageLoader::FrameChanged(imgIContainer *aContainer,
     return NS_OK;
   }
   
-  nsRect r(*dirtyRect);
-
-  r.x = nsPresContext::CSSPixelsToAppUnits(r.x);
-  r.y = nsPresContext::CSSPixelsToAppUnits(r.y);
-  r.width = nsPresContext::CSSPixelsToAppUnits(r.width);
-  r.height = nsPresContext::CSSPixelsToAppUnits(r.height);
+  nsRect r(nsIntRect::ToAppUnits(*dirtyRect, nsPresContext::AppUnitsPerCSSPixel()));
 
   RedrawDirtyFrame(&r);
 
diff --git a/layout/base/nsImageLoader.h b/layout/base/nsImageLoader.h
index 578ea40a56f1..9f8fc129b2ab 100644
--- a/layout/base/nsImageLoader.h
+++ b/layout/base/nsImageLoader.h
@@ -67,7 +67,7 @@ public:
 
   // imgIContainerObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD FrameChanged(imgIContainer *aContainer, gfxIImageFrame *newframe,
-                          nsRect * dirtyRect);
+                          nsIntRect *dirtyRect);
 
   void Init(nsIFrame *aFrame, nsPresContext *aPresContext,
             PRBool aReflowOnLoad);
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 6c817e739a70..2a4ff459c117 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -816,11 +816,11 @@ nsLayoutUtils::GetEventCoordinatesForNearestView(nsEvent* aEvent,
                                GUIEvent->refPoint, frameView);
 }
 
-static nsPoint GetWidgetOffset(nsIWidget* aWidget, nsIWidget*& aRootWidget) {
-  nsPoint offset(0, 0);
+static nsIntPoint GetWidgetOffset(nsIWidget* aWidget, nsIWidget*& aRootWidget) {
+  nsIntPoint offset(0, 0);
   nsIWidget* parent = aWidget->GetParent();
   while (parent) {
-    nsRect bounds;
+    nsIntRect bounds;
     aWidget->GetBounds(bounds);
     offset += bounds.TopLeft();
     aWidget = parent;
@@ -839,9 +839,9 @@ nsLayoutUtils::TranslateWidgetToView(nsPresContext* aPresContext,
   nsIWidget* viewWidget = aView->GetNearestWidget(&viewOffset);
 
   nsIWidget* fromRoot;
-  nsPoint fromOffset = GetWidgetOffset(aWidget, fromRoot);
+  nsIntPoint fromOffset(GetWidgetOffset(aWidget, fromRoot));
   nsIWidget* toRoot;
-  nsPoint toOffset = GetWidgetOffset(viewWidget, toRoot);
+  nsIntPoint toOffset(GetWidgetOffset(viewWidget, toRoot));
 
   nsIntPoint widgetPoint;
   if (fromRoot == toRoot) {
@@ -1986,7 +1986,7 @@ nsLayoutUtils::IntrinsicForContainer(nsIRenderingContext *aRenderingContext,
 
   const nsStyleDisplay *disp = aFrame->GetStyleDisplay();
   if (aFrame->IsThemed(disp)) {
-    nsSize size(0, 0);
+    nsIntSize size(0, 0);
     PRBool canOverride = PR_TRUE;
     nsPresContext *presContext = aFrame->PresContext();
     presContext->GetTheme()->
diff --git a/layout/base/nsPresContext.h b/layout/base/nsPresContext.h
index 25fa1b463ee7..3b95988e52c3 100644
--- a/layout/base/nsPresContext.h
+++ b/layout/base/nsPresContext.h
@@ -565,7 +565,7 @@ public:
                           mDeviceContext->AppUnitsPerInch()); }
 
   // Margin-specific version, since they often need TwipsToAppUnits
-  nsMargin TwipsToAppUnits(const nsMargin &marginInTwips) const
+  nsMargin TwipsToAppUnits(const nsIntMargin &marginInTwips) const
   { return nsMargin(TwipsToAppUnits(marginInTwips.left), 
                     TwipsToAppUnits(marginInTwips.top),
                     TwipsToAppUnits(marginInTwips.right),
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 5189cd8008ee..1b0c476135bd 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -887,12 +887,12 @@ public:
 
   virtual already_AddRefed<gfxASurface> RenderNode(nsIDOMNode* aNode,
                                                    nsIRegion* aRegion,
-                                                   nsPoint& aPoint,
-                                                   nsRect* aScreenRect);
+                                                   nsIntPoint& aPoint,
+                                                   nsIntRect* aScreenRect);
 
   virtual already_AddRefed<gfxASurface> RenderSelection(nsISelection* aSelection,
-                                                        nsPoint& aPoint,
-                                                        nsRect* aScreenRect);
+                                                        nsIntPoint& aPoint,
+                                                        nsIntRect* aScreenRect);
 
   //nsIViewObserver interface
 
@@ -1097,8 +1097,8 @@ protected:
                       nsISelection* aSelection,
                       nsIRegion* aRegion,
                       nsRect aArea,
-                      nsPoint& aPoint,
-                      nsRect* aScreenRect);
+                      nsIntPoint& aPoint,
+                      nsIntRect* aScreenRect);
 
   /**
    * Methods to handle changes to user and UA sheet lists that we get
@@ -5158,8 +5158,8 @@ PresShell::PaintRangePaintInfo(nsTArray<nsAutoPtr<RangePaintInfo> >* aItems,
                                nsISelection* aSelection,
                                nsIRegion* aRegion,
                                nsRect aArea,
-                               nsPoint& aPoint,
-                               nsRect* aScreenRect)
+                               nsIntPoint& aPoint,
+                               nsIntRect* aScreenRect)
 {
   nsPresContext* pc = GetPresContext();
   if (!pc || aArea.width == 0 || aArea.height == 0)
@@ -5168,8 +5168,7 @@ PresShell::PaintRangePaintInfo(nsTArray<nsAutoPtr<RangePaintInfo> >* aItems,
   nsIDeviceContext* deviceContext = pc->DeviceContext();
 
   // use the rectangle to create the surface
-  nsRect pixelArea = aArea;
-  pixelArea.ScaleRoundOut(1.0 / pc->AppUnitsPerDevPixel());
+  nsIntRect pixelArea(nsRect::ToOutsidePixels(aArea, pc->AppUnitsPerDevPixel()));
 
   // if the area of the image is larger than the maximum area, scale it down
   float scale = 0.0;
@@ -5273,8 +5272,8 @@ PresShell::PaintRangePaintInfo(nsTArray<nsAutoPtr<RangePaintInfo> >* aItems,
 already_AddRefed<gfxASurface>
 PresShell::RenderNode(nsIDOMNode* aNode,
                       nsIRegion* aRegion,
-                      nsPoint& aPoint,
-                      nsRect* aScreenRect)
+                      nsIntPoint& aPoint,
+                      nsIntRect* aScreenRect)
 {
   // area will hold the size of the surface needed to draw the node, measured
   // from the root frame.
@@ -5298,12 +5297,11 @@ PresShell::RenderNode(nsIDOMNode* aNode,
 
   if (aRegion) {
     // combine the area with the supplied region
-    nsRect rrectPixels;
+    nsIntRect rrectPixels;
     aRegion->GetBoundingBox(&rrectPixels.x, &rrectPixels.y,
                             &rrectPixels.width, &rrectPixels.height);
 
-    nsRect rrect = rrectPixels;
-    rrect.ScaleRoundOut(nsPresContext::AppUnitsPerCSSPixel());
+    nsRect rrect(nsIntRect::ToAppUnits(rrectPixels, nsPresContext::AppUnitsPerCSSPixel()));
     area.IntersectRect(area, rrect);
     
     nsPresContext* pc = GetPresContext();
@@ -5321,8 +5319,8 @@ PresShell::RenderNode(nsIDOMNode* aNode,
 
 already_AddRefed<gfxASurface>
 PresShell::RenderSelection(nsISelection* aSelection,
-                           nsPoint& aPoint,
-                           nsRect* aScreenRect)
+                           nsIntPoint& aPoint,
+                           nsIntRect* aScreenRect)
 {
   // area will hold the size of the surface needed to draw the selection,
   // measured from the root frame.
@@ -6709,6 +6707,37 @@ LogVerifyMessage(nsIFrame* k1, nsIFrame* k2, const char* aMsg,
   printf("  %s\n", aMsg);
 }
 
+static void
+LogVerifyMessage(nsIFrame* k1, nsIFrame* k2, const char* aMsg,
+                 const nsIntRect& r1, const nsIntRect& r2)
+{
+  printf("VerifyReflow Error:\n");
+  nsAutoString name;
+  nsIFrameDebug*  frameDebug;
+
+  if (NS_SUCCEEDED(k1->QueryInterface(NS_GET_IID(nsIFrameDebug),
+                                      (void**)&frameDebug))) {
+    fprintf(stdout, "  ");
+    frameDebug->GetFrameName(name);
+    fputs(NS_LossyConvertUTF16toASCII(name).get(), stdout);
+    fprintf(stdout, " %p ", (void*)k1);
+  }
+  printf("{%d, %d, %d, %d}", r1.x, r1.y, r1.width, r1.height);
+
+  printf(" != \n");
+
+  if (NS_SUCCEEDED(k2->QueryInterface(NS_GET_IID(nsIFrameDebug),
+                                      (void**)&frameDebug))) {
+    fprintf(stdout, "  ");
+    frameDebug->GetFrameName(name);
+    fputs(NS_LossyConvertUTF16toASCII(name).get(), stdout);
+    fprintf(stdout, " %p ", (void*)k2);
+  }
+  printf("{%d, %d, %d, %d}\n", r2.x, r2.y, r2.width, r2.height);
+
+  printf("  %s\n", aMsg);
+}
+
 static PRBool
 CompareTrees(nsPresContext* aFirstPresContext, nsIFrame* aFirstFrame, 
              nsPresContext* aSecondPresContext, nsIFrame* aSecondFrame)
@@ -6736,7 +6765,7 @@ CompareTrees(nsPresContext* aFirstPresContext, nsIFrame* aFirstFrame,
       }
     }
 
-    nsRect r1, r2;
+    nsIntRect r1, r2;
     nsIView* v1, *v2;
     for (;;) {
       if (((nsnull == k1) && (nsnull != k2)) ||
diff --git a/layout/generic/nsBulletFrame.cpp b/layout/generic/nsBulletFrame.cpp
index 927c67fde8d0..025f451d2f8c 100644
--- a/layout/generic/nsBulletFrame.cpp
+++ b/layout/generic/nsBulletFrame.cpp
@@ -72,12 +72,12 @@ public:
   // imgIDecoderObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage);
   NS_IMETHOD OnDataAvailable(imgIRequest *aRequest, gfxIImageFrame *aFrame,
-                             const nsRect *aRect);
+                             const nsIntRect *aRect);
   NS_IMETHOD OnStopDecode(imgIRequest *aRequest, nsresult status,
                           const PRUnichar *statusArg);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD FrameChanged(imgIContainer *aContainer, gfxIImageFrame *newframe,
-                          nsRect * dirtyRect);
+                          nsIntRect *dirtyRect);
 
   void SetFrame(nsBulletFrame *frame) { mFrame = frame; }
 
@@ -1462,7 +1462,7 @@ NS_IMETHODIMP nsBulletFrame::OnStartContainer(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsBulletFrame::OnDataAvailable(imgIRequest *aRequest,
                                              gfxIImageFrame *aFrame,
-                                             const nsRect *aRect)
+                                             const nsIntRect *aRect)
 {
   // The image has changed.
   // Invalidate the entire content area. Maybe it's not optimal but it's simple and
@@ -1493,7 +1493,7 @@ NS_IMETHODIMP nsBulletFrame::OnStopDecode(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsBulletFrame::FrameChanged(imgIContainer *aContainer,
                                           gfxIImageFrame *aNewFrame,
-                                          nsRect *aDirtyRect)
+                                          nsIntRect *aDirtyRect)
 {
   // Invalidate the entire content area. Maybe it's not optimal but it's simple and
   // always correct.
@@ -1551,7 +1551,7 @@ NS_IMETHODIMP nsBulletListener::OnStartContainer(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsBulletListener::OnDataAvailable(imgIRequest *aRequest,
                                                 gfxIImageFrame *aFrame,
-                                                const nsRect *aRect)
+                                                const nsIntRect *aRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
@@ -1571,7 +1571,7 @@ NS_IMETHODIMP nsBulletListener::OnStopDecode(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsBulletListener::FrameChanged(imgIContainer *aContainer,
                                              gfxIImageFrame *newframe,
-                                             nsRect * dirtyRect)
+                                             nsIntRect *dirtyRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
diff --git a/layout/generic/nsBulletFrame.h b/layout/generic/nsBulletFrame.h
index 42e16faf5142..1ba738bdafc7 100644
--- a/layout/generic/nsBulletFrame.h
+++ b/layout/generic/nsBulletFrame.h
@@ -82,13 +82,13 @@ public:
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage);
   NS_IMETHOD OnDataAvailable(imgIRequest *aRequest,
                              gfxIImageFrame *aFrame,
-                             const nsRect * rect);
+                             const nsIntRect *aRect);
   NS_IMETHOD OnStopDecode(imgIRequest *aRequest,
                           nsresult aStatus,
                           const PRUnichar *aStatusArg);
   NS_IMETHOD FrameChanged(imgIContainer *aContainer,
                           gfxIImageFrame *aNewframe,
-                          nsRect *aDirtyRect);
+                          nsIntRect *aDirtyRect);
 
   /* get list item text, without '.' */
   static PRBool AppendCounterText(PRInt32 aListStyleType,
diff --git a/layout/generic/nsFrame.cpp b/layout/generic/nsFrame.cpp
index 7cf7208e3ef9..00742c5e5444 100644
--- a/layout/generic/nsFrame.cpp
+++ b/layout/generic/nsFrame.cpp
@@ -584,16 +584,15 @@ nsIFrame::GetUsedBorder() const
 
   const nsStyleDisplay *disp = GetStyleDisplay();
   if (mutable_this->IsThemed(disp)) {
-    nsMargin result;
+    nsIntMargin result;
     nsPresContext *presContext = PresContext();
     presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
                                              mutable_this, disp->mAppearance,
                                              &result);
-    result.top = presContext->DevPixelsToAppUnits(result.top);
-    result.right = presContext->DevPixelsToAppUnits(result.right);
-    result.bottom = presContext->DevPixelsToAppUnits(result.bottom);
-    result.left = presContext->DevPixelsToAppUnits(result.left);
-    return result;
+    return nsMargin(presContext->DevPixelsToAppUnits(result.top),
+                    presContext->DevPixelsToAppUnits(result.right),
+                    presContext->DevPixelsToAppUnits(result.bottom),
+                    presContext->DevPixelsToAppUnits(result.left));
   }
 
   return GetStyleBorder()->GetActualBorder();
@@ -616,14 +615,15 @@ nsIFrame::GetUsedPadding() const
   const nsStyleDisplay *disp = GetStyleDisplay();
   if (mutable_this->IsThemed(disp)) {
     nsPresContext *presContext = PresContext();
+    nsIntMargin widget;
     if (presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
                                                   mutable_this,
                                                   disp->mAppearance,
-                                                  &padding)) {
-      padding.top = presContext->DevPixelsToAppUnits(padding.top);
-      padding.right = presContext->DevPixelsToAppUnits(padding.right);
-      padding.bottom = presContext->DevPixelsToAppUnits(padding.bottom);
-      padding.left = presContext->DevPixelsToAppUnits(padding.left);
+                                                  &widget)) {
+      padding.top = presContext->DevPixelsToAppUnits(widget.top);
+      padding.right = presContext->DevPixelsToAppUnits(widget.right);
+      padding.bottom = presContext->DevPixelsToAppUnits(widget.bottom);
+      padding.left = presContext->DevPixelsToAppUnits(widget.left);
       return padding;
     }
   }
@@ -816,9 +816,9 @@ void nsDisplaySelectionOverlay::Paint(nsDisplayListBuilder* aBuilder,
 
   nsRect rect(aBuilder->ToReferenceFrame(mFrame), mFrame->GetSize());
   rect.IntersectRect(rect, aDirtyRect);
-  rect.ScaleRoundOut(1.0f / mFrame->PresContext()->AppUnitsPerDevPixel());
+  nsIntRect pxRect(nsRect::ToOutsidePixels(rect, mFrame->PresContext()->AppUnitsPerDevPixel()));
   ctx->NewPath();
-  ctx->Rectangle(gfxRect(rect.x, rect.y, rect.width, rect.height), PR_TRUE);
+  ctx->Rectangle(gfxRect(pxRect.x, pxRect.y, pxRect.width, pxRect.height), PR_TRUE);
   ctx->Fill();
 }
 
@@ -3067,13 +3067,13 @@ nsFrame::IntrinsicWidthOffsets(nsIRenderingContext* aRenderingContext)
   if (IsThemed(disp)) {
     nsPresContext *presContext = PresContext();
 
-    nsMargin border;
+    nsIntMargin border;
     presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
                                              this, disp->mAppearance,
                                              &border);
     result.hBorder = presContext->DevPixelsToAppUnits(border.LeftRight());
 
-    nsMargin padding;
+    nsIntMargin padding;
     if (presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
                                                   this, disp->mAppearance,
                                                   &padding)) {
@@ -3184,15 +3184,16 @@ nsFrame::ComputeSize(nsIRenderingContext *aRenderingContext,
 
   const nsStyleDisplay *disp = GetStyleDisplay();
   if (IsThemed(disp)) {
-    nsSize size(0, 0);
+    nsIntSize widget(0, 0);
     PRBool canOverride = PR_TRUE;
     nsPresContext *presContext = PresContext();
     presContext->GetTheme()->
       GetMinimumWidgetSize(aRenderingContext, this, disp->mAppearance,
-                           &size, &canOverride);
+                           &widget, &canOverride);
 
-    size.width = presContext->DevPixelsToAppUnits(size.width);
-    size.height = presContext->DevPixelsToAppUnits(size.height);
+    nsSize size;
+    size.width = presContext->DevPixelsToAppUnits(widget.width);
+    size.height = presContext->DevPixelsToAppUnits(widget.height);
 
     // GMWS() returns border-box; we need content-box
     size.width -= aBorder.width + aPadding.width;
@@ -3549,9 +3550,7 @@ nsIntRect nsIFrame::GetScreenRectExternal() const
 
 nsIntRect nsIFrame::GetScreenRect() const
 {
-  nsRect r = GetScreenRectInAppUnits().ScaleRoundOutInverse(PresContext()->AppUnitsPerDevPixel());
-  // nsRect and nsIntRect are not necessarily the same
-  return nsIntRect(r.x, r.y, r.width, r.height);
+  return nsRect::ToOutsidePixels(GetScreenRectInAppUnits(), PresContext()->AppUnitsPerDevPixel());
 }
 
 // virtual
@@ -3571,7 +3570,6 @@ nsRect nsIFrame::GetScreenRectInAppUnits() const
     nsIWidget* widget = view->GetNearestWidget(&toWidgetOffset);
 
     if (widget) {
-      // WidgetToScreen really should take nsIntRect, not nsRect
       nsIntRect localRect(0,0,0,0), screenRect;
       widget->WidgetToScreen(localRect, screenRect);
 
diff --git a/layout/generic/nsFrameFrame.cpp b/layout/generic/nsFrameFrame.cpp
index c2672e3cb29e..53893da9dc6d 100644
--- a/layout/generic/nsFrameFrame.cpp
+++ b/layout/generic/nsFrameFrame.cpp
@@ -191,7 +191,7 @@ public:
   virtual void ReflowCallbackCanceled();
 
 protected:
-  nsSize GetMargin();
+  nsIntSize GetMargin();
   PRBool IsInline() { return mIsInline; }
   nsresult ShowDocShell();
   nsresult CreateViewAndWidget(nsContentType aContentType);
@@ -803,9 +803,9 @@ nsSubDocumentFrame::HideViewer()
   }
 }
 
-nsSize nsSubDocumentFrame::GetMargin()
+nsIntSize nsSubDocumentFrame::GetMargin()
 {
-  nsSize result(-1, -1);
+  nsIntSize result(-1, -1);
   nsGenericHTMLElement *content = nsGenericHTMLElement::FromContent(mContent);
   if (content) {
     const nsAttrValue* attr = content->GetParsedAttr(nsGkAtoms::marginwidth);
@@ -919,7 +919,7 @@ nsSubDocumentFrame::ShowDocShell()
 
   // pass along marginwidth, marginheight, scrolling so sub document
   // can use it
-  nsSize margin = GetMargin();
+  nsIntSize margin(GetMargin());
   docShell->SetMarginWidth(margin.width);
   docShell->SetMarginHeight(margin.height);
 
diff --git a/layout/generic/nsFrameSetFrame.cpp b/layout/generic/nsFrameSetFrame.cpp
index 459c236b2a80..1735c76e3f34 100644
--- a/layout/generic/nsFrameSetFrame.cpp
+++ b/layout/generic/nsFrameSetFrame.cpp
@@ -744,7 +744,7 @@ nsHTMLFramesetFrame* nsHTMLFramesetFrame::GetFramesetParent(nsIFrame* aChild)
 // only valid for non border children
 void nsHTMLFramesetFrame::GetSizeOfChildAt(PRInt32  aIndexInParent, 
                                            nsSize&  aSize, 
-                                           nsPoint& aCellIndex)
+                                           nsIntPoint& aCellIndex)
 {
   PRInt32 row = aIndexInParent / mNumCols;
   PRInt32 col = aIndexInParent - (row * mNumCols); // remainder from dividing index by mNumCols
@@ -754,7 +754,8 @@ void nsHTMLFramesetFrame::GetSizeOfChildAt(PRInt32  aIndexInParent,
     aCellIndex.x = col;
     aCellIndex.y = row;
   } else {
-    aSize.width = aSize.height = aCellIndex.x = aCellIndex.y = 0;
+    aSize.width = aSize.height = 0;
+    aCellIndex.x = aCellIndex.y = 0;
   }
 }
 
@@ -768,7 +769,7 @@ void nsHTMLFramesetFrame::GetSizeOfChild(nsIFrame* aChild,
   for (nsIFrame* child = mFrames.FirstChild(); child;
        child = child->GetNextSibling()) {
     if (aChild == child) {
-      nsPoint ignore;
+      nsIntPoint ignore;
       GetSizeOfChildAt(i, aSize, ignore);
       return;
     }
@@ -863,7 +864,7 @@ nsHTMLFramesetFrame::ReflowPlaceChild(nsIFrame*                aChild,
                                       const nsHTMLReflowState& aReflowState,
                                       nsPoint&                 aOffset,
                                       nsSize&                  aSize,
-                                      nsPoint*                 aCellIndex)
+                                      nsIntPoint*              aCellIndex)
 {
   // reflow the child
   nsHTMLReflowState  reflowState(aPresContext, aReflowState, aChild, aSize);
@@ -1068,7 +1069,7 @@ nsHTMLFramesetFrame::Reflow(nsPresContext*          aPresContext,
   nsIFrame* lastChild = mFrames.LastChild();
 
   for (PRInt32 childX = 0; childX < mNonBorderChildCount; childX++) {
-    nsPoint cellIndex;
+    nsIntPoint cellIndex;
     GetSizeOfChildAt(childX, size, cellIndex);
 
     if (lastRow != cellIndex.y) {  // changed to next row
diff --git a/layout/generic/nsFrameSetFrame.h b/layout/generic/nsFrameSetFrame.h
index 4b7de877a43f..9c045864452b 100644
--- a/layout/generic/nsFrameSetFrame.h
+++ b/layout/generic/nsFrameSetFrame.h
@@ -127,7 +127,7 @@ public:
 
   void GetSizeOfChildAt(PRInt32  aIndexInParent, 
                         nsSize&  aSize, 
-                        nsPoint& aCellIndex);
+                        nsIntPoint& aCellIndex);
 
   static nsHTMLFramesetFrame* GetFramesetParent(nsIFrame* aChild);
 
@@ -225,7 +225,7 @@ protected:
                         const nsHTMLReflowState& aReflowState,
                         nsPoint&                 aOffset,
                         nsSize&                  aSize,
-                        nsPoint*                 aCellIndex = 0);
+                        nsIntPoint*              aCellIndex = 0);
   
   PRBool CanResize(PRBool aVertical, 
                    PRBool aLeft); 
@@ -256,7 +256,7 @@ protected:
 
   nsHTMLFramesetBorderFrame* mDragger;
   nsFramesetDrag   mDrag;
-  nsPoint          mFirstDragPoint;
+  nsIntPoint       mFirstDragPoint;
   PRInt32          mPrevNeighborOrigSize; // used during resize
   PRInt32          mNextNeighborOrigSize;
   PRInt32          mMinDrag;
diff --git a/layout/generic/nsHTMLCanvasFrame.cpp b/layout/generic/nsHTMLCanvasFrame.cpp
index fc2c5425556b..761ad3398655 100644
--- a/layout/generic/nsHTMLCanvasFrame.cpp
+++ b/layout/generic/nsHTMLCanvasFrame.cpp
@@ -59,7 +59,7 @@ nsHTMLCanvasFrame::~nsHTMLCanvasFrame()
 {
 }
 
-nsSize
+nsIntSize
 nsHTMLCanvasFrame::GetCanvasSize()
 {
   PRUint32 w, h;
@@ -76,7 +76,7 @@ nsHTMLCanvasFrame::GetCanvasSize()
     h = w = 1;
   }
 
-  return nsSize(w, h);
+  return nsIntSize(w, h);
 }
 
 /* virtual */ nscoord
@@ -102,7 +102,9 @@ nsHTMLCanvasFrame::GetPrefWidth(nsIRenderingContext *aRenderingContext)
 /* virtual */ nsSize
 nsHTMLCanvasFrame::GetIntrinsicRatio()
 {
-  return GetCanvasSize();
+  nsIntSize size(GetCanvasSize());
+  return nsSize(nsPresContext::CSSPixelsToAppUnits(size.width),
+                nsPresContext::CSSPixelsToAppUnits(size.height));
 }
 
 /* virtual */ nsSize
@@ -111,13 +113,13 @@ nsHTMLCanvasFrame::ComputeSize(nsIRenderingContext *aRenderingContext,
                                nsSize aMargin, nsSize aBorder, nsSize aPadding,
                                PRBool aShrinkWrap)
 {
-  nsSize size = GetCanvasSize();
+  nsIntSize size(GetCanvasSize());
 
   IntrinsicSize intrinsicSize;
   intrinsicSize.width.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(size.width));
   intrinsicSize.height.SetCoordValue(nsPresContext::CSSPixelsToAppUnits(size.height));
 
-  nsSize& intrinsicRatio = size; // won't actually be used
+  nsSize intrinsicRatio(size.width, size.height); // won't actually be used
 
   return nsLayoutUtils::ComputeSizeWithIntrinsicDimensions(
                             aRenderingContext, this,
@@ -197,7 +199,7 @@ nsHTMLCanvasFrame::PaintCanvas(nsIRenderingContext& aRenderingContext,
   if (inner.width == 0 || inner.height == 0)
     return;
 
-  nsSize canvasSize = GetCanvasSize();
+  nsIntSize canvasSize(GetCanvasSize());
   nsSize sizeAppUnits(PresContext()->DevPixelsToAppUnits(canvasSize.width),
                       PresContext()->DevPixelsToAppUnits(canvasSize.height));
 
diff --git a/layout/generic/nsHTMLCanvasFrame.h b/layout/generic/nsHTMLCanvasFrame.h
index f16d0f589330..8b0d49496f3e 100644
--- a/layout/generic/nsHTMLCanvasFrame.h
+++ b/layout/generic/nsHTMLCanvasFrame.h
@@ -61,7 +61,7 @@ public:
                    const nsRect& aDirtyRect, nsPoint aPt);
                               
   /* get the size of the canvas's image */
-  nsSize GetCanvasSize();
+  nsIntSize GetCanvasSize();
 
   virtual nscoord GetMinWidth(nsIRenderingContext *aRenderingContext);
   virtual nscoord GetPrefWidth(nsIRenderingContext *aRenderingContext);
diff --git a/layout/generic/nsHTMLReflowState.cpp b/layout/generic/nsHTMLReflowState.cpp
index 3c0087fefd89..1c9edce2792e 100644
--- a/layout/generic/nsHTMLReflowState.cpp
+++ b/layout/generic/nsHTMLReflowState.cpp
@@ -1829,14 +1829,15 @@ nsCSSOffsetState::InitOffsets(nscoord aContainingBlockWidth,
   PRBool isThemed = frame->IsThemed(disp);
   nsPresContext *presContext = frame->PresContext();
 
+  nsIntMargin widget;
   if (isThemed &&
       presContext->GetTheme()->GetWidgetPadding(presContext->DeviceContext(),
                                                 frame, disp->mAppearance,
-                                                &mComputedPadding)) {
-    mComputedPadding.top = presContext->DevPixelsToAppUnits(mComputedPadding.top);
-    mComputedPadding.right = presContext->DevPixelsToAppUnits(mComputedPadding.right);
-    mComputedPadding.bottom = presContext->DevPixelsToAppUnits(mComputedPadding.bottom);
-    mComputedPadding.left = presContext->DevPixelsToAppUnits(mComputedPadding.left);
+                                                &widget)) {
+    mComputedPadding.top = presContext->DevPixelsToAppUnits(widget.top);
+    mComputedPadding.right = presContext->DevPixelsToAppUnits(widget.right);
+    mComputedPadding.bottom = presContext->DevPixelsToAppUnits(widget.bottom);
+    mComputedPadding.left = presContext->DevPixelsToAppUnits(widget.left);
   }
   else if (aPadding) { // padding is an input arg
     mComputedPadding.top    = aPadding->top;
@@ -1849,17 +1850,18 @@ nsCSSOffsetState::InitOffsets(nscoord aContainingBlockWidth,
   }
 
   if (isThemed) {
+    nsIntMargin widget;
     presContext->GetTheme()->GetWidgetBorder(presContext->DeviceContext(),
                                              frame, disp->mAppearance,
-                                             &mComputedBorderPadding);
+                                             &widget);
     mComputedBorderPadding.top =
-      presContext->DevPixelsToAppUnits(mComputedBorderPadding.top);
+      presContext->DevPixelsToAppUnits(widget.top);
     mComputedBorderPadding.right =
-      presContext->DevPixelsToAppUnits(mComputedBorderPadding.right);
+      presContext->DevPixelsToAppUnits(widget.right);
     mComputedBorderPadding.bottom =
-      presContext->DevPixelsToAppUnits(mComputedBorderPadding.bottom);
+      presContext->DevPixelsToAppUnits(widget.bottom);
     mComputedBorderPadding.left =
-      presContext->DevPixelsToAppUnits(mComputedBorderPadding.left);
+      presContext->DevPixelsToAppUnits(widget.left);
   }
   else if (aBorder) {  // border is an input arg
     mComputedBorderPadding = *aBorder;
diff --git a/layout/generic/nsImageFrame.cpp b/layout/generic/nsImageFrame.cpp
index 52712112e904..73980542fccc 100644
--- a/layout/generic/nsImageFrame.cpp
+++ b/layout/generic/nsImageFrame.cpp
@@ -303,7 +303,7 @@ nsImageFrame::UpdateIntrinsicSize(imgIContainer* aImage)
   PRBool intrinsicSizeChanged = PR_FALSE;
   
   if (aImage) {
-    nsSize imageSizeInPx;
+    nsIntSize imageSizeInPx;
     aImage->GetWidth(&imageSizeInPx.width);
     aImage->GetHeight(&imageSizeInPx.height);
     nsSize newSize(nsPresContext::CSSPixelsToAppUnits(imageSizeInPx.width),
@@ -387,7 +387,7 @@ nsImageFrame::IsPendingLoad(imgIContainer* aContainer) const
 }
 
 nsRect
-nsImageFrame::SourceRectToDest(const nsRect& aRect)
+nsImageFrame::SourceRectToDest(const nsIntRect& aRect)
 {
   // When scaling the image, row N of the source image may (depending on
   // the scaling function) be used to draw any row in the destination image
@@ -532,7 +532,7 @@ nsImageFrame::OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage)
 nsresult
 nsImageFrame::OnDataAvailable(imgIRequest *aRequest,
                               gfxIImageFrame *aFrame,
-                              const nsRect *aRect)
+                              const nsIntRect *aRect)
 {
   // XXX do we need to make sure that the reflow from the
   // OnStartContainer has been processed before we start calling
@@ -644,7 +644,7 @@ nsImageFrame::OnStopDecode(imgIRequest *aRequest,
 nsresult
 nsImageFrame::FrameChanged(imgIContainer *aContainer,
                            gfxIImageFrame *aNewFrame,
-                           nsRect *aDirtyRect)
+                           nsIntRect *aDirtyRect)
 {
   if (!GetStyleVisibility()->IsVisible()) {
     return NS_OK;
@@ -1838,7 +1838,7 @@ NS_IMETHODIMP nsImageListener::OnStartContainer(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsImageListener::OnDataAvailable(imgIRequest *aRequest,
                                                gfxIImageFrame *aFrame,
-                                               const nsRect *aRect)
+                                               const nsIntRect *aRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
@@ -1858,7 +1858,7 @@ NS_IMETHODIMP nsImageListener::OnStopDecode(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsImageListener::FrameChanged(imgIContainer *aContainer,
                                             gfxIImageFrame *newframe,
-                                            nsRect * dirtyRect)
+                                            nsIntRect * dirtyRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
diff --git a/layout/generic/nsImageFrame.h b/layout/generic/nsImageFrame.h
index c1e66ae45766..d51589f1ce22 100644
--- a/layout/generic/nsImageFrame.h
+++ b/layout/generic/nsImageFrame.h
@@ -74,12 +74,12 @@ public:
   // imgIDecoderObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage);
   NS_IMETHOD OnDataAvailable(imgIRequest *aRequest, gfxIImageFrame *aFrame,
-                             const nsRect *aRect);
+                             const nsIntRect *aRect);
   NS_IMETHOD OnStopDecode(imgIRequest *aRequest, nsresult status,
                           const PRUnichar *statusArg);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD FrameChanged(imgIContainer *aContainer, gfxIImageFrame *newframe,
-                          nsRect * dirtyRect);
+                          nsIntRect * dirtyRect);
 
   void SetFrame(nsImageFrame *frame) { mFrame = frame; }
 
@@ -225,13 +225,13 @@ protected:
   nsresult OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage);
   nsresult OnDataAvailable(imgIRequest *aRequest,
                            gfxIImageFrame *aFrame,
-                           const nsRect * rect);
+                           const nsIntRect *rect);
   nsresult OnStopDecode(imgIRequest *aRequest,
                         nsresult aStatus,
                         const PRUnichar *aStatusArg);
   nsresult FrameChanged(imgIContainer *aContainer,
                         gfxIImageFrame *aNewframe,
-                        nsRect *aDirtyRect);
+                        nsIntRect *aDirtyRect);
 
 private:
   // random helpers
@@ -268,7 +268,7 @@ private:
    * Function to convert a dirty rect in the source image to a dirty
    * rect for the image frame.
    */
-  nsRect SourceRectToDest(const nsRect & aRect);
+  nsRect SourceRectToDest(const nsIntRect & aRect);
 
   nsImageMap*         mImageMap;
 
diff --git a/layout/generic/nsObjectFrame.cpp b/layout/generic/nsObjectFrame.cpp
index 52be4b169c83..0039f5c5dc4a 100644
--- a/layout/generic/nsObjectFrame.cpp
+++ b/layout/generic/nsObjectFrame.cpp
@@ -523,10 +523,6 @@ private:
 
 };
 
-#if defined(XP_WIN) || (defined(DO_DIRTY_INTERSECT) && defined(XP_MACOSX)) || defined(XP_OS2)
-static void ConvertAppUnitsToPixels(const nsPresContext& aPresContext, const nsRect& aTwipsRect, nsIntRect& aPixelRect);
-#endif
-
   // Mac specific code to fix up port position and clip during paint
 #ifdef XP_MACOSX
 
@@ -916,7 +912,7 @@ nsObjectFrame::FixupWindow(const nsSize& aSize)
 
   PRBool windowless = (window->type == nsPluginWindowType_Drawable);
 
-  nsPoint origin = GetWindowOriginInPixels(windowless);
+  nsIntPoint origin = GetWindowOriginInPixels(windowless);
 
   window->x = origin.x;
   window->y = origin.y;
@@ -963,7 +959,7 @@ nsObjectFrame::CallSetWindow()
 
   PRBool windowless = (window->type == nsPluginWindowType_Drawable);
 
-  nsPoint origin = GetWindowOriginInPixels(windowless);
+  nsIntPoint origin = GetWindowOriginInPixels(windowless);
 
   window->x = origin.x;
   window->y = origin.y;
@@ -1016,7 +1012,7 @@ nsObjectFrame::IsHidden(PRBool aCheckVisibilityStyle) const
   return PR_FALSE;
 }
 
-nsPoint nsObjectFrame::GetWindowOriginInPixels(PRBool aWindowless)
+nsIntPoint nsObjectFrame::GetWindowOriginInPixels(PRBool aWindowless)
 {
   nsIView * parentWithView;
   nsPoint origin(0,0);
@@ -1045,10 +1041,8 @@ nsPoint nsObjectFrame::GetWindowOriginInPixels(PRBool aWindowless)
     }  
   }
 
-  origin.x = PresContext()->AppUnitsToDevPixels(origin.x);
-  origin.y = PresContext()->AppUnitsToDevPixels(origin.y);
-
-  return origin;
+  return nsIntPoint(PresContext()->AppUnitsToDevPixels(origin.x),
+                    PresContext()->AppUnitsToDevPixels(origin.y));
 }
 
 NS_IMETHODIMP
@@ -1427,7 +1421,7 @@ nsObjectFrame::PaintPlugin(nsIRenderingContext& aRenderingContext,
       // check if we need to call SetWindow with updated parameters
       PRBool doupdatewindow = PR_FALSE;
       // the offset of the DC
-      nsPoint origin;
+      nsIntPoint origin;
 
       /*
        * Layout now has an optimized way of painting. Now we always get
@@ -1521,7 +1515,7 @@ nsObjectFrame::PaintPlugin(nsIRenderingContext& aRenderingContext,
            // and we can safely use this message to tell the plugin exactly where it is in all cases.
 
               origin = GetWindowOriginInPixels(PR_TRUE);
-              nsRect winlessRect = nsRect(origin, nsSize(window->width, window->height));
+              nsIntRect winlessRect(origin, nsIntSize(window->width, window->height));
               // XXX I don't think we can be certain that the location wrt to
               // the window only changes when the location wrt to the drawable
               // changes, but the hdc probably changes on every paint so
@@ -3710,8 +3704,8 @@ nsEventStatus nsPluginInstanceOwner::ProcessEvent(const nsGUIEvent& anEvent)
         const nsMouseEvent& mouseEvent =
           static_cast<const nsMouseEvent&>(anEvent);
         // Get reference point relative to screen:
-        nsRect windowRect(anEvent.refPoint, nsSize(1, 1));
-        nsRect rootPoint(-1,-1,1,1);
+        nsIntRect windowRect(anEvent.refPoint, nsIntSize(1, 1));
+        nsIntRect rootPoint(-1,-1,1,1);
         if (widget)
           widget->WidgetToScreen(windowRect, rootPoint);
 #ifdef MOZ_WIDGET_GTK2
@@ -3984,12 +3978,8 @@ void nsPluginInstanceOwner::Paint(const nsRect& aDirtyRect)
   // Convert dirty rect relative coordinates to absolute and also get the containerWidget
   ConvertRelativeToWindowAbsolute(mOwner, rel, abs, *getter_AddRefs(containerWidget));
 
-  nsRect absDirtyRect = nsRect(abs.x, abs.y, aDirtyRect.width, aDirtyRect.height);
-
   // Convert to absolute pixel values for the dirty rect
-  nsIntRect absDirtyRectInPixels;
-  ConvertAppUnitsToPixels(*mOwner->GetPresContext(), absDirtyRect,
-                          absDirtyRectInPixels);
+  nsIntRect absDirtyRect(nsRect::ToOutsidePixels(nsRect(abs, aDirtyRect), *mOwner->GetPresContext()->AppUnitsPerDevPixel()));
 #endif
 
   nsCOMPtr<nsIPluginWidget> pluginWidget = do_QueryInterface(mWidget);
@@ -4018,18 +4008,15 @@ void nsPluginInstanceOwner::Paint(const nsRect& aDirtyRect, HDC ndc)
 
   nsPluginWindow * window;
   GetWindow(window);
-  nsRect relDirtyRect = nsRect(aDirtyRect.x, aDirtyRect.y, aDirtyRect.width, aDirtyRect.height);
-  nsIntRect relDirtyRectInPixels;
-  ConvertAppUnitsToPixels(*mOwner->PresContext(), relDirtyRect,
-                          relDirtyRectInPixels);
+  nsIntRect relDirtyRect(nsRect::ToOutsidePixels(aDirtyRect, mOwner->PresContext()->AppUnitsPerDevPixel()));
 
   // we got dirty rectangle in relative window coordinates, but we
   // need it in absolute units and in the (left, top, right, bottom) form
   RECT drc;
-  drc.left   = relDirtyRectInPixels.x + window->x;
-  drc.top    = relDirtyRectInPixels.y + window->y;
-  drc.right  = drc.left + relDirtyRectInPixels.width;
-  drc.bottom = drc.top + relDirtyRectInPixels.height;
+  drc.left   = relDirtyRect.x + window->x;
+  drc.top    = relDirtyRect.y + window->y;
+  drc.right  = drc.left + relDirtyRect.width;
+  drc.bottom = drc.top + relDirtyRect.height;
 
   nsPluginEvent pluginEvent;
   pluginEvent.event = WM_PAINT;
@@ -4048,18 +4035,15 @@ void nsPluginInstanceOwner::Paint(const nsRect& aDirtyRect, HPS aHPS)
 
   nsPluginWindow * window;
   GetWindow(window);
-  nsRect relDirtyRect = nsRect(aDirtyRect.x, aDirtyRect.y, aDirtyRect.width, aDirtyRect.height);
-  nsIntRect relDirtyRectInPixels;
-  ConvertAppUnitsToPixels(*mOwner->PresContext(), relDirtyRect,
-                          relDirtyRectInPixels);
+  nsIntRect relDirtyRect(nsRect::ToOutsidePixels(aDirtyRect, mOwner->PresContext()->AppUnitsPerDevicePixel()));
 
   // we got dirty rectangle in relative window coordinates, but we
   // need it in absolute units and in the (left, top, right, bottom) form
   RECTL rectl;
-  rectl.xLeft   = relDirtyRectInPixels.x + window->x;
-  rectl.yBottom = relDirtyRectInPixels.y + window->y;
-  rectl.xRight  = rectl.xLeft + relDirtyRectInPixels.width;
-  rectl.yTop    = rectl.yBottom + relDirtyRectInPixels.height;
+  rectl.xLeft   = relDirtyRect.x + window->x;
+  rectl.yBottom = relDirtyRect.y + window->y;
+  rectl.xRight  = rectl.xLeft + relDirtyRect.width;
+  rectl.yTop    = rectl.yBottom + relDirtyRect.height;
 
   nsPluginEvent pluginEvent;
   pluginEvent.event = WM_PAINT;
@@ -4544,17 +4528,6 @@ void nsPluginInstanceOwner::SetPluginHost(nsIPluginHost* aHost)
   mPluginHost = aHost;
 }
 
-#if defined(XP_WIN) || (defined(DO_DIRTY_INTERSECT) && defined(XP_MACOSX)) || defined(XP_OS2)
-// convert frame coordinates from twips to pixels
-static void ConvertAppUnitsToPixels(const nsPresContext& aPresContext, const nsRect& aTwipsRect, nsIntRect& aPixelRect)
-{
-  aPixelRect.x = aPresContext.AppUnitsToDevPixels(aTwipsRect.x);
-  aPixelRect.y = aPresContext.AppUnitsToDevPixels(aTwipsRect.y);
-  aPixelRect.width = aPresContext.AppUnitsToDevPixels(aTwipsRect.width);
-  aPixelRect.height = aPresContext.AppUnitsToDevPixels(aTwipsRect.height);
-}
-#endif
-
   // Mac specific code to fix up the port location and clipping region
 #ifdef XP_MACOSX
 
@@ -4635,13 +4608,13 @@ WindowRef nsPluginInstanceOwner::FixUpPluginWindow(PRInt32 inPaintState)
     // use its native widget (an obj-c object) we have to go
     // from the widget's screen coordinates to its window coords
     // instead of straight to window coords.
-    nsRect geckoBounds;
+    nsIntRect geckoBounds;
     mWidget->GetBounds(geckoBounds);
     // we need a rect that is the entire *internal* rect, so the
     // x and y coords are 0, width is the same.
     geckoBounds.x = 0;
     geckoBounds.y = 0;
-    nsRect geckoScreenCoords;
+    nsIntRect geckoScreenCoords;
     mWidget->WidgetToScreen(geckoBounds, geckoScreenCoords);
 
     Rect windowRect;
diff --git a/layout/generic/nsObjectFrame.h b/layout/generic/nsObjectFrame.h
index f2ae3b7f1ccc..0a6be3b25f1c 100644
--- a/layout/generic/nsObjectFrame.h
+++ b/layout/generic/nsObjectFrame.h
@@ -175,7 +175,7 @@ protected:
 
   void NotifyContentObjectWrapper();
 
-  nsPoint GetWindowOriginInPixels(PRBool aWindowless);
+  nsIntPoint GetWindowOriginInPixels(PRBool aWindowless);
 
   static void PaintPrintPlugin(nsIFrame* aFrame,
                                nsIRenderingContext* aRenderingContext,
@@ -197,7 +197,7 @@ protected:
   friend class nsPluginInstanceOwner;
 private:
   nsRefPtr<nsPluginInstanceOwner> mInstanceOwner;
-  nsRect                mWindowlessRect;
+  nsIntRect                       mWindowlessRect;
 
   // For assertions that make it easier to determine if a crash is due
   // to the underlying problem described in bug 136927, and to prevent
diff --git a/layout/generic/nsPageFrame.cpp b/layout/generic/nsPageFrame.cpp
index d9a81c47e1ce..147801f854f0 100644
--- a/layout/generic/nsPageFrame.cpp
+++ b/layout/generic/nsPageFrame.cpp
@@ -545,9 +545,8 @@ nsPageFrame::PaintPageContent(nsIRenderingContext& aRenderingContext,
   aRenderingContext.Translate(framePos.x, framePos.y);
   // aPt translates to coords relative to this, then margins translate to
   // pageContentFrame's coords
-  rect -= framePos;
   aRenderingContext.Scale(scale, scale);
-  rect.ScaleRoundOut(1.0f / scale);
+  rect = (rect - framePos).ScaleRoundOutInverse(scale);
   // Make sure we don't draw where we aren't supposed to draw, especially
   // when printing selection
   nsRect clipRect(nsPoint(0, 0), pageContentFrame->GetSize());
diff --git a/layout/generic/nsSimplePageSequence.cpp b/layout/generic/nsSimplePageSequence.cpp
index d0339f62d076..84b92b7b663d 100644
--- a/layout/generic/nsSimplePageSequence.cpp
+++ b/layout/generic/nsSimplePageSequence.cpp
@@ -199,13 +199,13 @@ nsSimplePageSequenceFrame::Reflow(nsPresContext*          aPresContext,
 
   // now get out margins & edges
   if (mPageData->mPrintSettings) {
-    nsMargin unwriteableTwips;
+    nsIntMargin unwriteableTwips;
     mPageData->mPrintSettings->GetUnwriteableMarginInTwips(unwriteableTwips);
     NS_ASSERTION(unwriteableTwips.left  >= 0 && unwriteableTwips.top >= 0 &&
                  unwriteableTwips.right >= 0 && unwriteableTwips.bottom >= 0,
                  "Unwriteable twips should be non-negative");
 
-    nsMargin marginTwips;
+    nsIntMargin marginTwips;
     mPageData->mPrintSettings->GetMarginInTwips(marginTwips);
     mMargin = aPresContext->TwipsToAppUnits(marginTwips + unwriteableTwips);
 
@@ -213,11 +213,11 @@ nsSimplePageSequenceFrame::Reflow(nsPresContext*          aPresContext,
     mPageData->mPrintSettings->GetPrintRange(&printType);
     mPrintRangeType = printType;
 
-    nsMargin edgeTwips;
+    nsIntMargin edgeTwips;
     mPageData->mPrintSettings->GetEdgeInTwips(edgeTwips);
 
     // sanity check the values. three inches are sometimes needed
-    nscoord inchInTwips = NS_INCHES_TO_TWIPS(3.0);
+    PRInt32 inchInTwips = NS_INCHES_TO_TWIPS(3.0);
     edgeTwips.top = PR_MIN(PR_MAX(edgeTwips.top, 0), inchInTwips);
     edgeTwips.bottom = PR_MIN(PR_MAX(edgeTwips.bottom, 0), inchInTwips);
     edgeTwips.left = PR_MIN(PR_MAX(edgeTwips.left, 0), inchInTwips);
@@ -700,9 +700,8 @@ nsSimplePageSequenceFrame::PaintPageSequence(nsIRenderingContext& aRenderingCont
   aRenderingContext.PushState();
   nsPoint framePos = aPt;
   aRenderingContext.Translate(framePos.x, framePos.y);
-  rect -= framePos;
   aRenderingContext.Scale(scale, scale);
-  rect.ScaleRoundOut(1.0f / scale);
+  rect = (rect - framePos).ScaleRoundOutInverse(scale);
 
   // Now the rect and the rendering coordinates are are relative to this frame.
   // Loop over the pages and paint them.
diff --git a/layout/printing/nsPrintEngine.cpp b/layout/printing/nsPrintEngine.cpp
index 7be7f22845fb..f52732c1beae 100644
--- a/layout/printing/nsPrintEngine.cpp
+++ b/layout/printing/nsPrintEngine.cpp
@@ -2202,8 +2202,8 @@ nsPrintEngine::DoPrint(nsPrintObject * aPO)
           if (NS_SUCCEEDED(rv)) {
             mPrt->mPrintSettings->SetStartPageRange(startPageNum);
             mPrt->mPrintSettings->SetEndPageRange(endPageNum);
-            nsMargin marginTwips(0,0,0,0);
-            nsMargin unwrtMarginTwips(0,0,0,0);
+            nsIntMargin marginTwips(0,0,0,0);
+            nsIntMargin unwrtMarginTwips(0,0,0,0);
             mPrt->mPrintSettings->GetMarginInTwips(marginTwips);
             mPrt->mPrintSettings->GetUnwriteableMarginInTwips(unwrtMarginTwips);
             nsMargin totalMargin = poPresContext->TwipsToAppUnits(marginTwips + 
diff --git a/layout/svg/base/src/nsSVGEffects.cpp b/layout/svg/base/src/nsSVGEffects.cpp
index 8d639bfa427f..804427b8204b 100644
--- a/layout/svg/base/src/nsSVGEffects.cpp
+++ b/layout/svg/base/src/nsSVGEffects.cpp
@@ -127,8 +127,7 @@ nsSVGFilterProperty::UpdateRect()
 {
   nsSVGFilterFrame *filter = GetFilterFrame(nsnull);
   if (filter) {
-    mFilterRect = filter->GetFilterBBox(mFrame, nsnull);
-    mFilterRect.ScaleRoundOut(filter->PresContext()->AppUnitsPerDevPixel());
+    mFilterRect = nsIntRect::ToAppUnits(filter->GetFilterBBox(mFrame, nsnull), filter->PresContext()->AppUnitsPerDevPixel());
   } else {
     mFilterRect = nsRect();
   }
diff --git a/layout/svg/base/src/nsSVGForeignObjectFrame.cpp b/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
index 4dcbad2cf958..3b58b55477f4 100644
--- a/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
+++ b/layout/svg/base/src/nsSVGForeignObjectFrame.cpp
@@ -700,8 +700,7 @@ nsSVGForeignObjectFrame::InvalidateDirtyRect(nsSVGOuterSVGFrame* aOuter,
 
   nsPresContext* presContext = PresContext();
   nsCOMPtr<nsIDOMSVGMatrix> tm = GetTMIncludingOffset();
-  nsIntRect r = aRect;
-  r.ScaleRoundOut(1.0f / presContext->AppUnitsPerDevPixel());
+  nsIntRect r(nsRect::ToOutsidePixels(aRect, presContext->AppUnitsPerDevPixel()));
   float x = r.x, y = r.y, w = r.width, h = r.height;
   nsRect rect = GetTransformedRegion(x, y, w, h, tm, presContext);
 
diff --git a/layout/svg/base/src/nsSVGIntegrationUtils.cpp b/layout/svg/base/src/nsSVGIntegrationUtils.cpp
index 1f454d5f4367..b763d0920973 100644
--- a/layout/svg/base/src/nsSVGIntegrationUtils.cpp
+++ b/layout/svg/base/src/nsSVGIntegrationUtils.cpp
@@ -123,9 +123,9 @@ nsSVGIntegrationUtils::ComputeFrameEffectsRect(nsIFrame* aFrame,
   nsRect r = GetSVGBBox(firstFrame, aFrame, aOverflowRect, userSpaceRect);
   // r is relative to user space
   PRUint32 appUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
-  r.ScaleRoundOutInverse(appUnitsPerDevPixel);
-  r = filterFrame->GetFilterBBox(firstFrame, &r);
-  r.ScaleRoundOut(appUnitsPerDevPixel);
+  nsIntRect p(nsRect::ToOutsidePixels(r, appUnitsPerDevPixel));
+  p = filterFrame->GetFilterBBox(firstFrame, &p);
+  r = nsIntRect::ToAppUnits(p, appUnitsPerDevPixel);
   // Make it relative to aFrame again
   return r + userSpaceRect.TopLeft() - aFrame->GetOffsetTo(firstFrame);
 }
@@ -146,9 +146,9 @@ nsSVGIntegrationUtils::GetInvalidAreaForChangedSource(nsIFrame* aFrame,
   nsRect userSpaceRect = GetNonSVGUserSpace(firstFrame);
   nsPoint offset = aFrame->GetOffsetTo(firstFrame) - userSpaceRect.TopLeft();
   nsRect r = aInvalidRect + offset;
-  r.ScaleRoundOutInverse(appUnitsPerDevPixel);
-  r = filterFrame->GetInvalidationBBox(firstFrame, r);
-  r.ScaleRoundOut(appUnitsPerDevPixel);
+  nsIntRect p(nsRect::ToOutsidePixels(r, appUnitsPerDevPixel));
+  p = filterFrame->GetInvalidationBBox(firstFrame, p);
+  r = nsIntRect::ToAppUnits(p, appUnitsPerDevPixel);
   return r - offset;
 }
 
@@ -169,9 +169,9 @@ nsSVGIntegrationUtils::GetRequiredSourceForInvalidArea(nsIFrame* aFrame,
   nsRect userSpaceRect = GetNonSVGUserSpace(firstFrame);
   nsPoint offset = aFrame->GetOffsetTo(firstFrame) - userSpaceRect.TopLeft();
   nsRect r = aDamageRect + offset;
-  r.ScaleRoundOutInverse(appUnitsPerDevPixel);
-  r = filterFrame->GetSourceForInvalidArea(firstFrame, r);
-  r.ScaleRoundOut(appUnitsPerDevPixel);
+  nsIntRect p(nsRect::ToOutsidePixels(r, appUnitsPerDevPixel));
+  p = filterFrame->GetSourceForInvalidArea(firstFrame, p);
+  r = nsIntRect::ToAppUnits(p, appUnitsPerDevPixel);
   return r - offset;
 }
 
@@ -216,8 +216,7 @@ public:
     nsIRenderingContext::AutoPushTranslation push(ctx, -mOffset.x, -mOffset.y);
     nsRect dirty;
     if (aDirtyRect) {
-      dirty = *aDirtyRect;
-      dirty.ScaleRoundOut(nsIDeviceContext::AppUnitsPerCSSPixel());
+      dirty = nsIntRect::ToAppUnits(*aDirtyRect, nsIDeviceContext::AppUnitsPerCSSPixel());
       dirty += mOffset;
     } else {
       dirty = mInnerList->GetBounds(mBuilder);
@@ -290,8 +289,7 @@ nsSVGIntegrationUtils::PaintFramesWithEffects(nsIRenderingContext* aCtx,
 
   nsRect userSpaceRect = GetNonSVGUserSpace(firstFrame) + aBuilder->ToReferenceFrame(firstFrame);
   PRInt32 appUnitsPerDevPixel = aEffectsFrame->PresContext()->AppUnitsPerDevPixel();
-  userSpaceRect.ScaleRoundPreservingCentersInverse(appUnitsPerDevPixel);
-  userSpaceRect.ScaleRoundOut(appUnitsPerDevPixel);
+  userSpaceRect = nsIntRect::ToAppUnits(nsRect::ToNearestPixels(userSpaceRect, appUnitsPerDevPixel), appUnitsPerDevPixel);
   aCtx->Translate(userSpaceRect.x, userSpaceRect.y);
 
   nsCOMPtr<nsIDOMSVGMatrix> matrix = GetInitialMatrix(aEffectsFrame);
@@ -316,8 +314,7 @@ nsSVGIntegrationUtils::PaintFramesWithEffects(nsIRenderingContext* aCtx,
   /* Paint the child */
   if (filterFrame) {
     RegularFramePaintCallback paint(aBuilder, aInnerList, userSpaceRect.TopLeft());
-    nsRect r = aDirtyRect - userSpaceRect.TopLeft();
-    r.ScaleRoundOutInverse(appUnitsPerDevPixel);
+    nsIntRect r(nsRect::ToOutsidePixels(aDirtyRect - userSpaceRect.TopLeft(), appUnitsPerDevPixel));
     filterFrame->FilterPaint(&svgContext, aEffectsFrame, &paint, &r);
   } else {
     gfx->SetMatrix(savedCTM);
diff --git a/layout/svg/base/src/nsSVGOuterSVGFrame.cpp b/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
index d80c6f897d67..0ffc76499844 100644
--- a/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
+++ b/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
@@ -560,7 +560,7 @@ nsSVGOuterSVGFrame::Paint(nsIRenderingContext& aRenderingContext,
   PRTime start = PR_Now();
 #endif
 
-  dirtyRect.ScaleRoundOut(1.0f / PresContext()->AppUnitsPerDevPixel());
+  nsIntRect dirtyPxRect(nsRect::ToOutsidePixels(dirtyRect, PresContext()->AppUnitsPerDevPixel()));
 
   nsSVGRenderState ctx(&aRenderingContext);
 
@@ -575,7 +575,7 @@ nsSVGOuterSVGFrame::Paint(nsIRenderingContext& aRenderingContext,
   // paint children:
   for (nsIFrame* kid = mFrames.FirstChild(); kid;
        kid = kid->GetNextSibling()) {
-    nsSVGUtils::PaintChildWithEffects(&ctx, &dirtyRect, kid);
+    nsSVGUtils::PaintChildWithEffects(&ctx, &dirtyPxRect, kid);
   }
 
 #ifdef XP_MACOSX
diff --git a/layout/svg/base/src/nsSVGUtils.cpp b/layout/svg/base/src/nsSVGUtils.cpp
index 7b39b018b63d..a8d19f2515d2 100644
--- a/layout/svg/base/src/nsSVGUtils.cpp
+++ b/layout/svg/base/src/nsSVGUtils.cpp
@@ -585,8 +585,7 @@ nsRect
 nsSVGUtils::FindFilterInvalidation(nsIFrame *aFrame, const nsRect& aRect)
 {
   PRInt32 appUnitsPerDevPixel = aFrame->PresContext()->AppUnitsPerDevPixel();
-  nsRect rect = aRect;
-  rect.ScaleRoundOutInverse(appUnitsPerDevPixel);
+  nsIntRect rect(nsRect::ToOutsidePixels(aRect, appUnitsPerDevPixel));
 
   while (aFrame) {
     if (aFrame->GetStateBits() & NS_STATE_IS_OUTER_SVG)
@@ -602,8 +601,7 @@ nsSVGUtils::FindFilterInvalidation(nsIFrame *aFrame, const nsRect& aRect)
     aFrame = aFrame->GetParent();
   }
 
-  rect.ScaleRoundOut(appUnitsPerDevPixel);
-  return rect;
+  return nsIntRect::ToAppUnits(rect, appUnitsPerDevPixel);
 }
 
 void
@@ -997,8 +995,7 @@ nsSVGUtils::PaintChildWithEffects(nsSVGRenderState *aContext,
       if (!aDirtyRect->Intersects(filterFrame->GetFilterBBox(aFrame, nsnull)))
         return;
     } else {
-      nsRect rect = *aDirtyRect;
-      rect.ScaleRoundOut(aFrame->PresContext()->AppUnitsPerDevPixel());
+      nsRect rect(nsIntRect::ToAppUnits(*aDirtyRect, aFrame->PresContext()->AppUnitsPerDevPixel()));
       if (!rect.Intersects(aFrame->GetRect()))
         return;
     }
diff --git a/layout/xul/base/public/nsXULPopupManager.h b/layout/xul/base/public/nsXULPopupManager.h
index 1a3c5c2fff85..f62103e9288f 100644
--- a/layout/xul/base/public/nsXULPopupManager.h
+++ b/layout/xul/base/public/nsXULPopupManager.h
@@ -724,7 +724,7 @@ protected:
   // range parent and offset set in SetTriggerEvent
   nsCOMPtr<nsIDOMNode> mRangeParent;
   PRInt32 mRangeOffset;
-  nsPoint mCachedMousePoint;
+  nsIntPoint mCachedMousePoint;
 
   // set to the currently active menu bar, if any
   nsMenuBarFrame* mActiveMenuBar;
diff --git a/layout/xul/base/src/nsBox.cpp b/layout/xul/base/src/nsBox.cpp
index 237dd14b5e3f..f23eab955473 100644
--- a/layout/xul/base/src/nsBox.cpp
+++ b/layout/xul/base/src/nsBox.cpp
@@ -344,7 +344,7 @@ nsBox::GetBorder(nsMargin& aMargin)
     // Go to the theme for the border.
     nsPresContext *context = PresContext();
     if (gTheme->ThemeSupportsWidget(context, this, disp->mAppearance)) {
-      nsMargin margin(0, 0, 0, 0);
+      nsIntMargin margin(0, 0, 0, 0);
       gTheme->GetWidgetBorder(context->DeviceContext(), this,
                               disp->mAppearance, &margin);
       aMargin.top = context->DevPixelsToAppUnits(margin.top);
@@ -368,7 +368,7 @@ nsBox::GetPadding(nsMargin& aMargin)
     // Go to the theme for the padding.
     nsPresContext *context = PresContext();
     if (gTheme->ThemeSupportsWidget(context, this, disp->mAppearance)) {
-      nsMargin margin(0, 0, 0, 0);
+      nsIntMargin margin(0, 0, 0, 0);
       PRBool useThemePadding;
 
       useThemePadding = gTheme->GetWidgetPadding(context->DeviceContext(),
@@ -728,7 +728,7 @@ nsIBox::AddCSSMinSize(nsBoxLayoutState& aState, nsIBox* aBox, nsSize& aSize)
     if (display->mAppearance) {
       nsITheme *theme = aState.PresContext()->GetTheme();
       if (theme && theme->ThemeSupportsWidget(aState.PresContext(), aBox, display->mAppearance)) {
-        nsSize size;
+        nsIntSize size;
         nsIRenderingContext* rendContext = aState.GetRenderingContext();
         if (rendContext) {
           theme->GetMinimumWidgetSize(rendContext, aBox,
diff --git a/layout/xul/base/src/nsBoxObject.cpp b/layout/xul/base/src/nsBoxObject.cpp
index dce253a0bcf1..09a1b1f17dd5 100644
--- a/layout/xul/base/src/nsBoxObject.cpp
+++ b/layout/xul/base/src/nsBoxObject.cpp
@@ -159,10 +159,9 @@ nsBoxObject::GetPresShell(PRBool aFlushLayout)
 }
 
 nsresult 
-nsBoxObject::GetOffsetRect(nsRect& aRect)
+nsBoxObject::GetOffsetRect(nsIntRect& aRect)
 {
-  aRect.x = aRect.y = 0;
-  aRect.Empty();
+  aRect.SetRect(0, 0, 0, 0);
  
   if (!mContent)
     return NS_ERROR_NOT_INITIALIZED;
@@ -241,7 +240,7 @@ nsBoxObject::GetScreenPosition(nsIntPoint& aPoint)
 NS_IMETHODIMP
 nsBoxObject::GetX(PRInt32* aResult)
 {
-  nsRect rect;
+  nsIntRect rect;
   GetOffsetRect(rect);
   *aResult = rect.x;
   return NS_OK;
@@ -250,7 +249,7 @@ nsBoxObject::GetX(PRInt32* aResult)
 NS_IMETHODIMP 
 nsBoxObject::GetY(PRInt32* aResult)
 {
-  nsRect rect;
+  nsIntRect rect;
   GetOffsetRect(rect);
   *aResult = rect.y;
   return NS_OK;
@@ -259,7 +258,7 @@ nsBoxObject::GetY(PRInt32* aResult)
 NS_IMETHODIMP
 nsBoxObject::GetWidth(PRInt32* aResult)
 {
-  nsRect rect;
+  nsIntRect rect;
   GetOffsetRect(rect);
   *aResult = rect.width;
   return NS_OK;
@@ -268,7 +267,7 @@ nsBoxObject::GetWidth(PRInt32* aResult)
 NS_IMETHODIMP 
 nsBoxObject::GetHeight(PRInt32* aResult)
 {
-  nsRect rect;
+  nsIntRect rect;
   GetOffsetRect(rect);
   *aResult = rect.height;
   return NS_OK;
diff --git a/layout/xul/base/src/nsBoxObject.h b/layout/xul/base/src/nsBoxObject.h
index e0179aad4b63..4c1e7269da26 100644
--- a/layout/xul/base/src/nsBoxObject.h
+++ b/layout/xul/base/src/nsBoxObject.h
@@ -48,7 +48,7 @@
 
 class nsIFrame;
 class nsIDocShell;
-struct nsRect;
+struct nsIntRect;
 
 class nsBoxObject : public nsPIBoxObject
 {
@@ -66,7 +66,7 @@ public:
 
   nsIFrame* GetFrame(PRBool aFlushLayout);
   nsIPresShell* GetPresShell(PRBool aFlushLayout);
-  nsresult GetOffsetRect(nsRect& aRect);
+  nsresult GetOffsetRect(nsIntRect& aRect);
   nsresult GetScreenPosition(nsIntPoint& aPoint);
 
   // Given a parent frame and a child frame, find the frame whose
diff --git a/layout/xul/base/src/nsImageBoxFrame.cpp b/layout/xul/base/src/nsImageBoxFrame.cpp
index 334772aa6bb7..b767b10b53de 100644
--- a/layout/xul/base/src/nsImageBoxFrame.cpp
+++ b/layout/xul/base/src/nsImageBoxFrame.cpp
@@ -542,7 +542,7 @@ NS_IMETHODIMP nsImageBoxFrame::OnStopDecode(imgIRequest *request,
 
 NS_IMETHODIMP nsImageBoxFrame::FrameChanged(imgIContainer *container,
                                             gfxIImageFrame *newframe,
-                                            nsRect * dirtyRect)
+                                            nsIntRect *dirtyRect)
 {
   nsBoxLayoutState state(PresContext());
   this->Redraw(state);
@@ -590,7 +590,7 @@ NS_IMETHODIMP nsImageBoxListener::OnStopDecode(imgIRequest *request,
 
 NS_IMETHODIMP nsImageBoxListener::FrameChanged(imgIContainer *container,
                                                gfxIImageFrame *newframe,
-                                               nsRect * dirtyRect)
+                                               nsIntRect *dirtyRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
diff --git a/layout/xul/base/src/nsImageBoxFrame.h b/layout/xul/base/src/nsImageBoxFrame.h
index 2adfc907c904..f9d80e068297 100644
--- a/layout/xul/base/src/nsImageBoxFrame.h
+++ b/layout/xul/base/src/nsImageBoxFrame.h
@@ -60,7 +60,7 @@ public:
                           const PRUnichar *statusArg);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD FrameChanged(imgIContainer *container, gfxIImageFrame *newframe,
-                          nsRect * dirtyRect);
+                          nsIntRect *dirtyRect);
 
   void SetFrame(nsImageBoxFrame *frame) { mFrame = frame; }
 
@@ -123,7 +123,7 @@ public:
                           const PRUnichar *statusArg);
   NS_IMETHOD FrameChanged(imgIContainer *container,
                           gfxIImageFrame *newframe,
-                          nsRect * dirtyRect);
+                          nsIntRect *dirtyRect);
 
   virtual ~nsImageBoxFrame();
 
diff --git a/layout/xul/base/src/nsMenuPopupFrame.cpp b/layout/xul/base/src/nsMenuPopupFrame.cpp
index fa0b8b964452..100490523d05 100644
--- a/layout/xul/base/src/nsMenuPopupFrame.cpp
+++ b/layout/xul/base/src/nsMenuPopupFrame.cpp
@@ -1000,7 +1000,8 @@ nsMenuPopupFrame::SetPopupPosition(nsIFrame* aAnchorFrame)
     if (mAnchorContent) {
       anchorScreenRect = aAnchorFrame->GetScreenRectInAppUnits();
       // adjust for differences in the anchor frame's scaling
-      anchorScreenRect.ScaleRoundOut(adj);
+      anchorScreenRect = nsIntRect::ToAppUnits(nsRect::ToOutsidePixels(anchorScreenRect,
+                         aAnchorFrame->PresContext()->AppUnitsPerDevPixel()), presContext->AppUnitsPerDevPixel());
       xpos = anchorScreenRect.x - rootScreenRect.x;
       ypos = anchorScreenRect.y - rootScreenRect.y;
 
diff --git a/layout/xul/base/src/nsResizerFrame.h b/layout/xul/base/src/nsResizerFrame.h
index 81ba08400a14..c1a97b87ee64 100644
--- a/layout/xul/base/src/nsResizerFrame.h
+++ b/layout/xul/base/src/nsResizerFrame.h
@@ -65,7 +65,7 @@ protected:
                         PRInt32 aMovement, PRInt8 aResizerDirection);
 
 protected:
-	nsRect mWidgetRect;
+	nsIntRect mWidgetRect;
 }; // class nsResizerFrame
 
 #endif /* nsResizerFrame_h___ */
diff --git a/layout/xul/base/src/nsScrollBoxObject.cpp b/layout/xul/base/src/nsScrollBoxObject.cpp
index 4d8471c367de..5bbab4992d3e 100644
--- a/layout/xul/base/src/nsScrollBoxObject.cpp
+++ b/layout/xul/base/src/nsScrollBoxObject.cpp
@@ -290,9 +290,9 @@ NS_IMETHODIMP nsScrollBoxObject::ScrollToElement(nsIDOMElement *child)
     nsPoint cp;
     scrollableView->GetScrollPosition(cp.x,cp.y);
 
-    GetOffsetRect(crect);    
-    crect.x = nsPresContext::CSSPixelsToAppUnits(crect.x);
-    crect.y = nsPresContext::CSSPixelsToAppUnits(crect.y);
+    nsIntRect prect;
+    GetOffsetRect(prect);    
+    crect = nsIntRect::ToAppUnits(prect, nsPresContext::AppUnitsPerCSSPixel());
     nscoord newx=cp.x, newy=cp.y;
 
     // we only scroll in the direction of the scrollbox orientation
@@ -390,11 +390,9 @@ NS_IMETHODIMP nsScrollBoxObject::EnsureElementIsVisible(nsIDOMElement *child)
     // get our current info
     nsPoint cp;
     scrollableView->GetScrollPosition(cp.x,cp.y);
-    GetOffsetRect(crect);    
-    crect.x = nsPresContext::CSSPixelsToAppUnits(crect.x);
-    crect.y = nsPresContext::CSSPixelsToAppUnits(crect.y);
-    crect.width = nsPresContext::CSSPixelsToAppUnits(crect.width);
-    crect.height = nsPresContext::CSSPixelsToAppUnits(crect.height);
+    nsIntRect prect;
+    GetOffsetRect(prect);    
+    crect = nsIntRect::ToAppUnits(prect, nsPresContext::AppUnitsPerCSSPixel());
 
     nscoord newx=cp.x, newy=cp.y;
 
diff --git a/layout/xul/base/src/nsTitleBarFrame.cpp b/layout/xul/base/src/nsTitleBarFrame.cpp
index cfd4ef79a80d..4458d3341ded 100644
--- a/layout/xul/base/src/nsTitleBarFrame.cpp
+++ b/layout/xul/base/src/nsTitleBarFrame.cpp
@@ -159,7 +159,7 @@ nsTitleBarFrame::HandleEvent(nsPresContext* aPresContext,
    case NS_MOUSE_MOVE: {
        if(mTrackingMouseMove)
        {
-         nsPoint nsMoveBy = aEvent->refPoint - mLastPoint;
+         nsIntPoint nsMoveBy(aEvent->refPoint - mLastPoint);
 
          nsIFrame* parent = GetParent();
          while (parent && parent->GetType() != nsGkAtoms::menuPopupFrame)
@@ -171,7 +171,7 @@ nsTitleBarFrame::HandleEvent(nsPresContext* aPresContext,
            nsCOMPtr<nsIWidget> widget;
            (static_cast<nsMenuPopupFrame*>(parent))->
              GetWidget(getter_AddRefs(widget));
-           nsRect bounds;
+           nsIntRect bounds;
            widget->GetScreenBounds(bounds);
            widget->Move(bounds.x + nsMoveBy.x, bounds.y + nsMoveBy.y);
          }
diff --git a/layout/xul/base/src/nsTitleBarFrame.h b/layout/xul/base/src/nsTitleBarFrame.h
index 01156ebd0807..0e3828368874 100644
--- a/layout/xul/base/src/nsTitleBarFrame.h
+++ b/layout/xul/base/src/nsTitleBarFrame.h
@@ -70,7 +70,7 @@ protected:
 
 protected:
 	PRBool mTrackingMouseMove;	
-	nsPoint mLastPoint;
+	nsIntPoint mLastPoint;
 
 
 }; // class nsTitleBarFrame
diff --git a/layout/xul/base/src/nsXULPopupManager.cpp b/layout/xul/base/src/nsXULPopupManager.cpp
index 5d8ece253c0b..d6e8de87d566 100644
--- a/layout/xul/base/src/nsXULPopupManager.cpp
+++ b/layout/xul/base/src/nsXULPopupManager.cpp
@@ -308,7 +308,7 @@ nsXULPopupManager::GetMouseLocation(nsIDOMNode** aNode, PRInt32* aOffset)
 void
 nsXULPopupManager::SetTriggerEvent(nsIDOMEvent* aEvent, nsIContent* aPopup)
 {
-  mCachedMousePoint = nsPoint(0, 0);
+  mCachedMousePoint = nsIntPoint(0, 0);
 
   nsCOMPtr<nsIDOMNSUIEvent> uiEvent = do_QueryInterface(aEvent);
   if (uiEvent) {
@@ -338,15 +338,14 @@ nsXULPopupManager::SetTriggerEvent(nsIDOMEvent* aEvent, nsIContent* aPopup)
               mouseEvent->GetClientY(&mCachedMousePoint.y);
 
               // convert to device pixels
-              PRInt32 adj = presContext->DeviceContext()->AppUnitsPerDevPixel();
-              mCachedMousePoint.x = nsPresContext::CSSPixelsToAppUnits(mCachedMousePoint.x) / adj;
-              mCachedMousePoint.y = nsPresContext::CSSPixelsToAppUnits(mCachedMousePoint.y) / adj;
+              mCachedMousePoint.x = presContext->AppUnitsToDevPixels(nsPresContext::CSSPixelsToAppUnits(mCachedMousePoint.x));
+              mCachedMousePoint.y = presContext->AppUnitsToDevPixels(nsPresContext::CSSPixelsToAppUnits(mCachedMousePoint.y));
             }
             else if (rootFrame) {
               nsPoint pnt =
                 nsLayoutUtils::GetEventCoordinatesRelativeTo(event, rootFrame);
-              mCachedMousePoint = nsPoint(presContext->AppUnitsToDevPixels(pnt.x),
-                                          presContext->AppUnitsToDevPixels(pnt.y));
+              mCachedMousePoint = nsIntPoint(presContext->AppUnitsToDevPixels(pnt.x),
+                                             presContext->AppUnitsToDevPixels(pnt.y));
             }
           }
         }
@@ -999,7 +998,7 @@ nsXULPopupManager::FirePopupShowingEvent(nsIContent* aPopup,
                             GetClosestView()->GetNearestWidget(&pnt);
   event.refPoint = mCachedMousePoint;
   nsEventDispatcher::Dispatch(aPopup, aPresContext, &event, nsnull, &status);
-  mCachedMousePoint = nsPoint(0, 0);
+  mCachedMousePoint = nsIntPoint(0, 0);
 
   // if a panel, blur whatever has focus so that the panel can take the focus.
   // This is done after the popupshowing event in case that event is cancelled.
diff --git a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
index fd3c990fff57..94899dc95501 100644
--- a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
@@ -658,8 +658,7 @@ nsTreeBodyFrame::GetSelectionRegion(nsIScriptableRegion **aRegion)
   region->Init();
 
   nsRefPtr<nsPresContext> presContext = PresContext();
-  nsRect rect = mRect;
-  rect.ScaleRoundOut(1.0 / presContext->AppUnitsPerCSSPixel());
+  nsIntRect rect(nsRect::ToOutsidePixels(mRect, presContext->AppUnitsPerCSSPixel()));
 
   nsIFrame* rootFrame = presContext->PresShell()->GetRootFrame();
   nsPoint origin = GetOffsetTo(rootFrame);
@@ -2127,14 +2126,15 @@ nsTreeBodyFrame::GetTwistyRect(PRInt32 aRowIndex,
   }
 
   if (useTheme) {
-    nsSize minTwistySize(0,0);
+    nsIntSize minTwistySizePx(0,0);
     PRBool canOverride = PR_TRUE;
     theme->GetMinimumWidgetSize(&aRenderingContext, this, twistyDisplayData->mAppearance,
-                                &minTwistySize, &canOverride);
+                                &minTwistySizePx, &canOverride);
 
-    // GMWS() returns size in pixels, we need to convert it back to twips
-    minTwistySize.width = aPresContext->DevPixelsToAppUnits(minTwistySize.width);
-    minTwistySize.height = aPresContext->DevPixelsToAppUnits(minTwistySize.height);
+    // GMWS() returns size in pixels, we need to convert it back to app units
+    nsSize minTwistySize;
+    minTwistySize.width = aPresContext->DevPixelsToAppUnits(minTwistySizePx.width);
+    minTwistySize.height = aPresContext->DevPixelsToAppUnits(minTwistySizePx.height);
 
     if (aTwistyRect.width < minTwistySize.width || !canOverride)
       aTwistyRect.width = minTwistySize.width;
diff --git a/layout/xul/base/src/tree/src/nsTreeImageListener.cpp b/layout/xul/base/src/tree/src/nsTreeImageListener.cpp
index 55ee320e8203..c44e36482143 100644
--- a/layout/xul/base/src/tree/src/nsTreeImageListener.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeImageListener.cpp
@@ -65,7 +65,7 @@ NS_IMETHODIMP nsTreeImageListener::OnStartContainer(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsTreeImageListener::OnDataAvailable(imgIRequest *aRequest,
                                                    gfxIImageFrame *aFrame,
-                                                   const nsRect *aRect)
+                                                   const nsIntRect *aRect)
 {
   Invalidate();
   return NS_OK;
@@ -73,7 +73,7 @@ NS_IMETHODIMP nsTreeImageListener::OnDataAvailable(imgIRequest *aRequest,
 
 NS_IMETHODIMP nsTreeImageListener::FrameChanged(imgIContainer *aContainer,
                                                 gfxIImageFrame *newframe,
-                                                nsRect * dirtyRect)
+                                                nsIntRect *dirtyRect)
 {
   Invalidate();
   return NS_OK;
diff --git a/layout/xul/base/src/tree/src/nsTreeImageListener.h b/layout/xul/base/src/tree/src/nsTreeImageListener.h
index 3461c8fa4cd5..44b81a01a889 100644
--- a/layout/xul/base/src/tree/src/nsTreeImageListener.h
+++ b/layout/xul/base/src/tree/src/nsTreeImageListener.h
@@ -73,10 +73,10 @@ public:
   // imgIDecoderObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest, imgIContainer *aImage);
   NS_IMETHOD OnDataAvailable(imgIRequest *aRequest, gfxIImageFrame *aFrame,
-                             const nsRect *aRect);
+                             const nsIntRect *aRect);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD FrameChanged(imgIContainer *aContainer, gfxIImageFrame *newframe,
-                          nsRect * dirtyRect);
+                          nsIntRect *dirtyRect);
 
   NS_IMETHOD AddCell(PRInt32 aIndex, nsITreeColumn* aCol);
  
diff --git a/view/public/nsIViewManager.h b/view/public/nsIViewManager.h
index 49c03c336888..13c4a90d8235 100644
--- a/view/public/nsIViewManager.h
+++ b/view/public/nsIViewManager.h
@@ -60,10 +60,10 @@ enum nsRectVisibility {
   nsRectVisibility_kZeroAreaRect
 }; 
 
-// 7eae119d-9fc8-482d-92ec-145eef228a4a
+// de2a2d24-9753-4488-9fdc-dd0accb484f7
 #define NS_IVIEWMANAGER_IID   \
-{ 0x7eae119d, 0x9fc8, 0x482d, \
-  { 0x92, 0xec, 0x14, 0x5e, 0xef, 0x22, 0x8a, 0x4a } }
+{ 0xde2a2d24, 0x9753, 0x4488, \
+  { 0x9f, 0xdc, 0xdd, 0x0a, 0xcc, 0xb4, 0x84, 0xf7 } };
 
 class nsIViewManager : public nsISupports
 {
@@ -477,7 +477,7 @@ public:
    *                        otherwise it returns an enum indicating why not
    */
   NS_IMETHOD GetRectVisibility(nsIView *aView, const nsRect &aRect, 
-                               PRUint16 aMinTwips, 
+                               nscoord aMinTwips, 
                                nsRectVisibility *aRectVisibility)=0;
 
   /**
diff --git a/view/src/nsScrollPortView.cpp b/view/src/nsScrollPortView.cpp
index 53586af17452..4a3eb56508a6 100644
--- a/view/src/nsScrollPortView.cpp
+++ b/view/src/nsScrollPortView.cpp
@@ -515,7 +515,7 @@ NS_IMETHODIMP nsScrollPortView::CanScroll(PRBool aHorizontal,
   return NS_OK;
 }
 
-void nsScrollPortView::Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsPoint aPixDelta,
+void nsScrollPortView::Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsIntPoint aPixDelta,
                               PRInt32 aP2A)
 {
   if (aTwipsDelta.x != 0 || aTwipsDelta.y != 0)
@@ -565,10 +565,10 @@ void nsScrollPortView::Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsPoin
       // consistent with the view hierarchy.
       mViewManager->UpdateView(this, NS_VMREFRESH_DEFERRED);
     } else { // if we can blit and have a scrollwidget then scroll.
-      nsRect* toScrollPtr = nsnull;
+      nsIntRect* toScrollPtr = nsnull;
 
 #ifdef XP_WIN
-      nsRect toScroll;
+      nsIntRect toScroll;
       if (!updateRegion.IsEmpty()) {
         nsRegion regionToScroll;
         regionToScroll.Sub(nsRect(nsPoint(0,0), GetBounds().Size()),
@@ -577,15 +577,13 @@ void nsScrollPortView::Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsPoin
         nsRect biggestRect(0,0,0,0);
         const nsRect* r;
         for (r = iter.Next(); r; r = iter.Next()) {
-          if (r->width*r->height > biggestRect.width*biggestRect.height) {
+          if (PRInt64(r->width)*PRInt64(r->height) > PRInt64(biggestRect.width)*PRInt64(biggestRect.height)) {
             biggestRect = *r;
           }
         }
         toScrollPtr = &toScroll;
-        biggestRect.ScaleRoundIn(1.0/aP2A);
-        toScroll = biggestRect;
-        biggestRect *= aP2A;
-        regionToScroll.Sub(regionToScroll, biggestRect);
+        toScroll = nsRect::ToInsidePixels(biggestRect, aP2A);
+        regionToScroll.Sub(regionToScroll, nsIntRect::ToAppUnits(toScroll, aP2A));
         updateRegion.Or(updateRegion, regionToScroll);
       }
 #endif
@@ -671,7 +669,7 @@ NS_IMETHODIMP nsScrollPortView::ScrollToImpl(nscoord aX, nscoord aY, PRUint32 aU
   mOffsetX = aX;
   mOffsetY = aY;
 
-  Scroll(scrolledView, twipsDelta, nsPoint(dxPx, dyPx), p2a);
+  Scroll(scrolledView, twipsDelta, nsIntPoint(dxPx, dyPx), p2a);
 
   mViewManager->SynthesizeMouseMove(PR_TRUE);
   
diff --git a/view/src/nsScrollPortView.h b/view/src/nsScrollPortView.h
index 0df4ec113e02..c9208af07c4b 100644
--- a/view/src/nsScrollPortView.h
+++ b/view/src/nsScrollPortView.h
@@ -102,7 +102,7 @@ protected:
   virtual ~nsScrollPortView();
 
   //private
-  void Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsPoint aPixDelta, PRInt32 p2a);
+  void Scroll(nsView *aScrolledView, nsPoint aTwipsDelta, nsIntPoint aPixDelta, nscoord aP2A);
   PRBool CannotBitBlt(nsView* aScrolledView);
 
   nscoord             mOffsetX, mOffsetY;
diff --git a/view/src/nsView.cpp b/view/src/nsView.cpp
index 2999eee03a21..fa4f11a3e47a 100644
--- a/view/src/nsView.cpp
+++ b/view/src/nsView.cpp
@@ -356,7 +356,7 @@ void nsView::ResetWidgetBounds(PRBool aRecurse, PRBool aMoveOnly,
   }
 }
 
-nsRect nsView::CalcWidgetBounds(nsWindowType aType)
+nsIntRect nsView::CalcWidgetBounds(nsWindowType aType)
 {
   nsCOMPtr<nsIDeviceContext> dx;
   mViewManager->GetDeviceContext(*getter_AddRefs(dx));
@@ -373,15 +373,14 @@ nsRect nsView::CalcWidgetBounds(nsWindowType aType)
 
     if (parentWidget && aType == eWindowType_popup &&
         mVis == nsViewVisibility_kShow) {
-      nsRect screenRect(0,0,1,1);
+      nsIntRect screenRect(0,0,1,1);
       parentWidget->WidgetToScreen(screenRect, screenRect);
       viewBounds += nsPoint(NSIntPixelsToAppUnits(screenRect.x, p2a),
                             NSIntPixelsToAppUnits(screenRect.y, p2a));
     }
   }
 
-  nsRect newBounds(viewBounds);
-  newBounds.ScaleRoundPreservingCentersInverse(p2a);
+  nsIntRect newBounds(nsRect::ToNearestPixels(viewBounds, p2a));
 
   nsPoint roundedOffset(NSIntPixelsToAppUnits(newBounds.x, p2a),
                         NSIntPixelsToAppUnits(newBounds.y, p2a));
@@ -398,7 +397,7 @@ void nsView::DoResetWidgetBounds(PRBool aMoveOnly,
     return;
   }
   
-  nsRect curBounds;
+  nsIntRect curBounds;
   mWindow->GetBounds(curBounds);
   nsWindowType type;
   mWindow->GetWindowType(type);
@@ -414,7 +413,7 @@ void nsView::DoResetWidgetBounds(PRBool aMoveOnly,
 
   NS_PRECONDITION(mWindow, "Why was this called??");
 
-  nsRect newBounds = CalcWidgetBounds(type);
+  nsIntRect newBounds = CalcWidgetBounds(type);
 
   PRBool changedPos = curBounds.TopLeft() != newBounds.TopLeft();
   PRBool changedSize = curBounds.Size() != newBounds.Size();
@@ -636,9 +635,9 @@ nsresult nsIView::CreateWidget(const nsIID &aWindowIID,
 
   nsView* v = static_cast<nsView*>(this);
 
-  nsRect trect = v->CalcWidgetBounds(aWidgetInitData
-                                     ? aWidgetInitData->mWindowType
-                                     : eWindowType_child);
+  nsIntRect trect = v->CalcWidgetBounds(aWidgetInitData
+                                        ? aWidgetInitData->mWindowType
+                                        : eWindowType_child);
 
   if (NS_OK == v->LoadWidget(aWindowIID))
   {
@@ -755,17 +754,15 @@ void nsIView::List(FILE* out, PRInt32 aIndent) const
   for (i = aIndent; --i >= 0; ) fputs("  ", out);
   fprintf(out, "%p ", (void*)this);
   if (nsnull != mWindow) {
-    nsRect windowBounds;
-    nsRect nonclientBounds;
-    float p2t;
     nsIDeviceContext *dx;
     mViewManager->GetDeviceContext(dx);
-    p2t = (float) dx->AppUnitsPerDevPixel();
+    nscoord p2a = dx->AppUnitsPerDevPixel();
     NS_RELEASE(dx);
-    mWindow->GetClientBounds(windowBounds);
-    windowBounds *= p2t;
-    mWindow->GetBounds(nonclientBounds);
-    nonclientBounds *= p2t;
+    nsIntRect rect;
+    mWindow->GetClientBounds(rect);
+    nsRect windowBounds(nsIntRect::ToAppUnits(rect, p2a));
+    mWindow->GetBounds(rect);
+    nsRect nonclientBounds(nsIntRect::ToAppUnits(rect, p2a));
     nsrefcnt widgetRefCnt = mWindow->AddRef() - 1;
     mWindow->Release();
     PRInt32 Z;
diff --git a/view/src/nsView.h b/view/src/nsView.h
index a99aae5656ef..4e23dd89119e 100644
--- a/view/src/nsView.h
+++ b/view/src/nsView.h
@@ -192,7 +192,7 @@ public:
     return mViewToWidgetOffset;
   }
 
-  nsRect CalcWidgetBounds(nsWindowType aType);
+  nsIntRect CalcWidgetBounds(nsWindowType aType);
 
 protected:
   // Do the actual work of ResetWidgetBounds, unconditionally.  Don't
diff --git a/view/src/nsViewManager.cpp b/view/src/nsViewManager.cpp
index 4905839da1a6..4a23c1f36421 100644
--- a/view/src/nsViewManager.cpp
+++ b/view/src/nsViewManager.cpp
@@ -868,8 +868,7 @@ nsViewManager::UpdateWidgetArea(nsView *aWidgetView, const nsRegion &aDamagedReg
 
     const nsRect* r;
     for (nsRegionRectIterator iter(leftOver); (r = iter.Next());) {
-      nsRect bounds = *r;
-      ViewToWidget(aWidgetView, aWidgetView, bounds);
+      nsIntRect bounds(ViewToWidget(aWidgetView, aWidgetView, *r));
       widget->Invalidate(bounds, PR_FALSE);
     }
   }
@@ -1009,14 +1008,6 @@ void nsViewManager::SuppressFocusEvents(PRBool aSuppress)
 
 }
 
-static void ConvertRectAppUnitsToIntPixels(nsRect& aRect, PRInt32 p2a)
-{
-  aRect.x = NSAppUnitsToIntPixels(aRect.x, p2a);
-  aRect.y = NSAppUnitsToIntPixels(aRect.y, p2a);
-  aRect.width = NSAppUnitsToIntPixels(aRect.width, p2a);
-  aRect.height = NSAppUnitsToIntPixels(aRect.height, p2a);
-}
-
 NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aStatus)
 {
   *aStatus = nsEventStatus_eIgnore;
@@ -1066,7 +1057,7 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
           if (NS_FAILED(CreateRegion(getter_AddRefs(region))))
             break;
 
-          const nsRect& damrect = *event->rect;
+          const nsIntRect& damrect = *event->rect;
           region->SetTo(damrect.x, damrect.y, damrect.width, damrect.height);
         }
         
@@ -1148,10 +1139,9 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
         } else {
           // since we got an NS_PAINT event, we need to
           // draw something so we don't get blank areas.
-          nsRect damRect;
-          region->GetBoundingBox(&damRect.x, &damRect.y, &damRect.width, &damRect.height);
-          PRInt32 p2a = mContext->AppUnitsPerDevPixel();
-          damRect.ScaleRoundOut(float(p2a));
+          nsIntRect damIntRect;
+          region->GetBoundingBox(&damIntRect.x, &damIntRect.y, &damIntRect.width, &damIntRect.height);
+          nsRect damRect(nsIntRect::ToAppUnits(damIntRect, mContext->AppUnitsPerDevPixel()));
           DefaultRefresh(view, event->renderingContext, &damRect);
         
           // Clients like the editor can trigger multiple
@@ -1290,8 +1280,8 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
             nsPoint rootOffset = baseView->GetDimensions().TopLeft();
             rootOffset += baseView->GetOffsetTo(RootViewManager()->mRootView);
             RootViewManager()->mMouseLocation = aEvent->refPoint +
-                nsPoint(NSAppUnitsToIntPixels(rootOffset.x, p2a),
-                        NSAppUnitsToIntPixels(rootOffset.y, p2a));
+                nsIntPoint(NSAppUnitsToIntPixels(rootOffset.x, p2a),
+                           NSAppUnitsToIntPixels(rootOffset.y, p2a));
 #ifdef DEBUG_MOUSE_LOCATION
             if (aEvent->message == NS_MOUSE_ENTER)
               printf("[vm=%p]got mouse enter for %p\n",
@@ -1309,7 +1299,7 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
             // won't matter at all since we'll get the mouse move or
             // enter after the mouse exit when the mouse moves from one
             // of our widgets into another.
-            RootViewManager()->mMouseLocation = nsPoint(NSCOORD_NONE, NSCOORD_NONE);
+            RootViewManager()->mMouseLocation = nsIntPoint(NSCOORD_NONE, NSCOORD_NONE);
 #ifdef DEBUG_MOUSE_LOCATION
             printf("[vm=%p]got mouse exit for %p\n",
                    this, aEvent->widget);
@@ -1346,26 +1336,6 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
           pt += offset;
 
           *aStatus = HandleEvent(view, pt, aEvent, capturedEvent);
-
-          //
-          // need to map the reply back into platform coordinates
-          //
-          switch (aEvent->message) {
-            case NS_TEXT_TEXT:
-              ConvertRectAppUnitsToIntPixels(
-                ((nsTextEvent*)aEvent)->theReply.mCursorPosition, p2a);
-              break;
-            case NS_COMPOSITION_START:
-            case NS_COMPOSITION_QUERY:
-              ConvertRectAppUnitsToIntPixels(
-                ((nsCompositionEvent*)aEvent)->theReply.mCursorPosition, p2a);
-              break;
-            case NS_QUERY_CHARACTER_RECT:
-            case NS_QUERY_CARET_RECT:
-              ConvertRectAppUnitsToIntPixels(
-                ((nsQueryContentEvent*)aEvent)->mReply.mRect, p2a);
-              break;
-          }
         }
     
         break;
@@ -2050,25 +2020,26 @@ nsPoint nsViewManager::ComputeViewOffset(const nsView *aView)
   return origin;
 }
 
-void nsViewManager::ViewToWidget(nsView *aView, nsView* aWidgetView, nsRect &aRect) const
+nsIntRect nsViewManager::ViewToWidget(nsView *aView, nsView* aWidgetView, const nsRect &aRect) const
 {
+  nsRect rect = aRect;
   while (aView != aWidgetView) {
-    aView->ConvertToParentCoords(&aRect.x, &aRect.y);
+    aView->ConvertToParentCoords(&rect.x, &rect.y);
     aView = aView->GetParent();
   }
   
   // intersect aRect with bounds of aWidgetView, to prevent generating any illegal rectangles.
   nsRect bounds;
   aWidgetView->GetDimensions(bounds);
-  aRect.IntersectRect(aRect, bounds);
+  rect.IntersectRect(rect, bounds);
   // account for the view's origin not lining up with the widget's
-  aRect.x -= bounds.x;
-  aRect.y -= bounds.y;
-
-  aRect += aView->ViewToWidgetOffset();
+  rect.x -= bounds.x;
+  rect.y -= bounds.y;
+  
+  rect += aView->ViewToWidgetOffset();
 
   // finally, convert to device coordinates.
-  aRect.ScaleRoundOut(1.0f / mContext->AppUnitsPerDevPixel());
+  return nsRect::ToOutsidePixels(rect, mContext->AppUnitsPerDevPixel());
 }
 
 nsresult nsViewManager::GetVisibleRect(nsRect& aVisibleRect)
@@ -2126,7 +2097,7 @@ nsresult nsViewManager::GetAbsoluteRect(nsView *aView, const nsRect &aRect,
 
 NS_IMETHODIMP nsViewManager::GetRectVisibility(nsIView *aView, 
                                                const nsRect &aRect,
-                                               PRUint16 aMinTwips, 
+                                               nscoord aMinTwips, 
                                                nsRectVisibility *aRectVisibility)
 {
   nsView* view = static_cast<nsView*>(aView);
@@ -2317,7 +2288,7 @@ nsViewManager::SynthesizeMouseMove(PRBool aFromScroll)
   if (!IsRootVM())
     return RootViewManager()->SynthesizeMouseMove(aFromScroll);
 
-  if (mMouseLocation == nsPoint(NSCOORD_NONE, NSCOORD_NONE))
+  if (mMouseLocation == nsIntPoint(NSCOORD_NONE, NSCOORD_NONE))
     return NS_OK;
 
   if (!mSynthMouseMoveEvent.IsPending()) {
@@ -2372,7 +2343,7 @@ nsViewManager::ProcessSynthMouseMoveEvent(PRBool aFromScroll)
 
   NS_ASSERTION(IsRootVM(), "Only the root view manager should be here");
 
-  if (mMouseLocation == nsPoint(NSCOORD_NONE, NSCOORD_NONE) || !mRootView) {
+  if (mMouseLocation == nsIntPoint(NSCOORD_NONE, NSCOORD_NONE) || !mRootView) {
     mSynthMouseMoveEvent.Forget();
     return;
   }
@@ -2386,20 +2357,20 @@ nsViewManager::ProcessSynthMouseMoveEvent(PRBool aFromScroll)
          this, mMouseLocation.x, mMouseLocation.y);
 #endif
                                                        
-  nsPoint pt = mMouseLocation;
+  nsPoint pt;
   PRInt32 p2a = mContext->AppUnitsPerDevPixel();
   pt.x = NSIntPixelsToAppUnits(mMouseLocation.x, p2a);
   pt.y = NSIntPixelsToAppUnits(mMouseLocation.y, p2a);
   // This could be a bit slow (traverses entire view hierarchy)
   // but it's OK to do it once per synthetic mouse event
   nsView* view = FindFloatingViewContaining(mRootView, pt);
-  nsPoint offset(0, 0);
+  nsIntPoint offset(0, 0);
   if (!view) {
     view = mRootView;
   } else {
-    offset = view->GetOffsetTo(mRootView);
-    offset.x = NSAppUnitsToIntPixels(offset.x, p2a);
-    offset.y = NSAppUnitsToIntPixels(offset.y, p2a);
+    nsPoint viewoffset(view->GetOffsetTo(mRootView));
+    offset.x = NSAppUnitsToIntPixels(viewoffset.x, p2a);
+    offset.y = NSAppUnitsToIntPixels(viewoffset.y, p2a);
   }
   nsMouseEvent event(PR_TRUE, NS_MOUSE_MOVE, view->GetWidget(),
                      nsMouseEvent::eSynthesized);
diff --git a/view/src/nsViewManager.h b/view/src/nsViewManager.h
index 87d1671eeda8..ed22cfbf2e9a 100644
--- a/view/src/nsViewManager.h
+++ b/view/src/nsViewManager.h
@@ -193,7 +193,7 @@ public:
    *                        otherwise it returns an enum indicating why not
    */
   NS_IMETHOD GetRectVisibility(nsIView *aView, const nsRect &aRect, 
-                               PRUint16 aMinTwips, 
+                               nscoord aMinTwips, 
                                nsRectVisibility *aRectVisibility);
 
   NS_IMETHOD SynthesizeMouseMove(PRBool aFromScroll);
@@ -291,7 +291,7 @@ private:
    * system of the widget attached to aWidgetView, which should be an ancestor
    * of aView.
    */
-  void ViewToWidget(nsView *aView, nsView* aWidgetView, nsRect &aRect) const;
+  nsIntRect ViewToWidget(nsView *aView, nsView* aWidgetView, const nsRect &aRect) const;
 
   /**
    * Transforms a rectangle from specified view's coordinate system to
@@ -433,7 +433,7 @@ private:
   nsIViewObserver   *mObserver;
   nsIScrollableView *mRootScrollable;
   nscolor           mDefaultBackgroundColor;
-  nsPoint           mMouseLocation; // device units, relative to mRootView
+  nsIntPoint        mMouseLocation; // device units, relative to mRootView
 
   // The size for a resize that we delayed until the root view becomes
   // visible again.
diff --git a/widget/public/nsGUIEvent.h b/widget/public/nsGUIEvent.h
index 651932cf5a59..c1c2abefd7e8 100644
--- a/widget/public/nsGUIEvent.h
+++ b/widget/public/nsGUIEvent.h
@@ -445,7 +445,7 @@ public:
   // See GUI MESSAGES,
   PRUint32    message;
   // In widget relative coordinates, not modified by layout code.
-  nsPoint     refPoint;
+  nsIntPoint  refPoint;
   // Elapsed time, in milliseconds, from a platform-specific zero time
   // to the time the message was created
   PRUint32    time;
@@ -531,7 +531,7 @@ public:
   }
 
   /// x,y width, height in pixels (client area)
-  nsRect          *windowSize;    
+  nsIntRect       *windowSize;    
   /// width of entire window (in pixels)
   PRInt32         mWinWidth;    
   /// height of entire window (in pixels)
@@ -593,7 +593,7 @@ public:
   /// area to paint  (should be used instead of rect)
   nsIRegion           *region;
   /// x,y, width, height in pixels of area to paint
-  nsRect              *rect;      
+  nsIntRect           *rect;      
 };
 
 /**
@@ -822,7 +822,7 @@ struct nsTextEventReply
   {
   }
 
-  nsRect mCursorPosition;
+  nsIntRect mCursorPosition;
   PRBool mCursorIsCollapsed;
   nsIWidget* mReferenceWidget;
 };
@@ -961,7 +961,7 @@ public:
     void* mContentsRoot;
     PRUint32 mOffset;
     nsString mString;
-    nsRect mRect; // Finally, the coordinates is system coordinates.
+    nsIntRect mRect; // Finally, the coordinates is system coordinates.
     // The return widget has the caret. This is set at all query events.
     nsIWidget* mFocusedWidget;
   } mReply;
diff --git a/widget/public/nsIPrintSettings.idl b/widget/public/nsIPrintSettings.idl
index df33258d19f2..da351bb6cc6b 100644
--- a/widget/public/nsIPrintSettings.idl
+++ b/widget/public/nsIPrintSettings.idl
@@ -49,7 +49,7 @@
 /**
  * Native types
  */
-  [ref] native nsNativeMarginRef(nsMargin);
+  [ref] native nsNativeIntMarginRef(nsIntMargin);
   
 interface nsIPrintSession;
 
@@ -58,7 +58,7 @@ interface nsIPrintSession;
  *
  * @status UNDER_REVIEW
  */
-[scriptable, uuid(5af07661-6477-4235-8814-4a45215855b8)]
+[scriptable, uuid(343700dd-078b-42b6-a809-b9c1d7e951d0)]
 
 interface nsIPrintSettings : nsISupports
 {
@@ -304,11 +304,11 @@ interface nsIPrintSettings : nsISupports
   attribute boolean isInitializedFromPrefs;
 
   /* C++ Helper Functions */
-  [noscript] void SetMarginInTwips(in nsNativeMarginRef aMargin);
-  [noscript] void SetEdgeInTwips(in nsNativeMarginRef aEdge);
+  [noscript] void SetMarginInTwips(in nsNativeIntMarginRef aMargin);
+  [noscript] void SetEdgeInTwips(in nsNativeIntMarginRef aEdge);
   /* Purposely made this an "in" arg */
-  [noscript] void GetMarginInTwips(in nsNativeMarginRef aMargin);
-  [noscript] void GetEdgeInTwips(in nsNativeMarginRef aEdge);
+  [noscript] void GetMarginInTwips(in nsNativeIntMarginRef aMargin);
+  [noscript] void GetEdgeInTwips(in nsNativeIntMarginRef aEdge);
 
   /**
    * We call this function so that anything that requires a run of the event loop
@@ -329,6 +329,6 @@ interface nsIPrintSettings : nsISupports
    * negative margin values by falling back on the system default for
    * that margin.
    */
-  [noscript] void SetUnwriteableMarginInTwips(in nsNativeMarginRef aEdge);
-  [noscript] void GetUnwriteableMarginInTwips(in nsNativeMarginRef aEdge);
+  [noscript] void SetUnwriteableMarginInTwips(in nsNativeIntMarginRef aEdge);
+  [noscript] void GetUnwriteableMarginInTwips(in nsNativeIntMarginRef aEdge);
 };
diff --git a/widget/public/nsIScreenManager.idl b/widget/public/nsIScreenManager.idl
index 7c218e2f9f0f..c06419458ab3 100644
--- a/widget/public/nsIScreenManager.idl
+++ b/widget/public/nsIScreenManager.idl
@@ -46,7 +46,7 @@ interface nsIScreenManager : nsISupports
     // Returns the screen that contains the rectangle. If the rect overlaps
     // multiple screens, it picks the screen with the greatest area of intersection.
     //
-    // The coordinates are in pixels (not twips) and in screen coordinates.
+    // The coordinates are in pixels (not app units) and in screen coordinates.
     //
   nsIScreen screenForRect ( in long left, in long top, in long width, in long height ) ;
   
diff --git a/widget/public/nsIWidget.h b/widget/public/nsIWidget.h
index 84edd0af3fef..0da3afbcbdca 100644
--- a/widget/public/nsIWidget.h
+++ b/widget/public/nsIWidget.h
@@ -93,10 +93,10 @@ typedef nsEventStatus (*PR_CALLBACK EVENT_CALLBACK)(nsGUIEvent *event);
 #define NS_NATIVE_PLUGIN_PORT_CG    101
 #endif
 
-// 0e64821f-00a2-4adc-ac3b-3439d61f4491
+// a85944af-7fce-4e45-bf04-ac12c823394b
 #define NS_IWIDGET_IID \
-{ 0x0e64821f, 0x00a2, 0x4adc, \
-  { 0xac, 0x3b, 0x34, 0x39, 0xd6, 0x1f, 0x44, 0x91 } }
+{ 0xa85944af, 0x7fce, 0x4e45, \
+  { 0xbf, 0x04, 0xac, 0x12, 0xc8, 0x23, 0x39, 0x4b } }
 
 // Hide the native window systems real window type so as to avoid
 // including native window system types and APIs. This is necessary
@@ -312,7 +312,7 @@ class nsIWidget : public nsISupports {
      *
      */
     NS_IMETHOD Create(nsIWidget        *aParent,
-                        const nsRect     &aRect,
+                        const nsIntRect  &aRect,
                         EVENT_CALLBACK   aHandleEventFunction,
                         nsIDeviceContext *aContext,
                         nsIAppShell      *aAppShell = nsnull,
@@ -339,7 +339,7 @@ class nsIWidget : public nsISupports {
      * @param     aHandleEventFunction the event handler callback function
      */
     NS_IMETHOD Create(nsNativeWidget aParent,
-                        const nsRect     &aRect,
+                        const nsIntRect  &aRect,
                         EVENT_CALLBACK   aHandleEventFunction,
                         nsIDeviceContext *aContext,
                         nsIAppShell      *aAppShell = nsnull,
@@ -583,7 +583,7 @@ class nsIWidget : public nsISupports {
      * @param aRect on return it holds the  x, y, width and height of this widget
      *
      */
-    NS_IMETHOD GetBounds(nsRect &aRect) = 0;
+    NS_IMETHOD GetBounds(nsIntRect &aRect) = 0;
 
 
     /**
@@ -596,7 +596,7 @@ class nsIWidget : public nsISupports {
      * @param aRect on return it holds the  x, y, width and height of this widget
      *
      */
-    NS_IMETHOD GetScreenBounds(nsRect &aRect) = 0;
+    NS_IMETHOD GetScreenBounds(nsIntRect &aRect) = 0;
 
 
     /**
@@ -606,7 +606,7 @@ class nsIWidget : public nsISupports {
      * @param aRect on return it holds the  x. y, width and height of the client area of this widget
      *
      */
-    NS_IMETHOD GetClientBounds(nsRect &aRect) = 0;
+    NS_IMETHOD GetClientBounds(nsIntRect &aRect) = 0;
 
     /**
      * Gets the width and height of the borders
@@ -745,7 +745,7 @@ class nsIWidget : public nsISupports {
      * @see #Update()
      */
 
-    NS_IMETHOD Invalidate(const nsRect & aRect, PRBool aIsSynchronous) = 0;
+    NS_IMETHOD Invalidate(const nsIntRect & aRect, PRBool aIsSynchronous) = 0;
 
     /**
      * Invalidate a specified region for a widget and repaints it.
@@ -802,7 +802,7 @@ class nsIWidget : public nsISupports {
      *
      */
 
-    NS_IMETHOD Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *aClipRect) = 0;
+    NS_IMETHOD Scroll(PRInt32 aDx, PRInt32 aDy, nsIntRect *aClipRect) = 0;
 
     /**
      * Scroll the contents of the widget. 
@@ -826,7 +826,7 @@ class nsIWidget : public nsISupports {
      *
      */
 
-    NS_IMETHOD ScrollRect(nsRect &aSrcRect, PRInt32 aDx, PRInt32 aDy) = 0;
+    NS_IMETHOD ScrollRect(nsIntRect &aSrcRect, PRInt32 aDx, PRInt32 aDy) = 0;
 
     /** 
      * Internal methods
@@ -896,7 +896,7 @@ class nsIWidget : public nsISupports {
      * @param  aNewRect  screen coordinates stored in the x,y members
      */
 
-    NS_IMETHOD WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect) = 0;
+    NS_IMETHOD WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect) = 0;
 
     /**
      * Convert from screen coordinates to this widget's coordinates.
@@ -905,7 +905,7 @@ class nsIWidget : public nsISupports {
      * @param  aNewRect  widget's coordinates stored in the x,y members
      */
 
-    NS_IMETHOD ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect) = 0;
+    NS_IMETHOD ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect) = 0;
 
     /**
      * When adjustments are to made to a whole set of child widgets, call this
diff --git a/widget/src/cocoa/nsChildView.h b/widget/src/cocoa/nsChildView.h
index c11a07223785..04afec500566 100644
--- a/widget/src/cocoa/nsChildView.h
+++ b/widget/src/cocoa/nsChildView.h
@@ -259,14 +259,14 @@ public:
 
   // nsIWidget interface
   NS_IMETHOD              Create(nsIWidget *aParent,
-                                 const nsRect &aRect,
+                                 const nsIntRect &aRect,
                                  EVENT_CALLBACK aHandleEventFunction,
                                  nsIDeviceContext *aContext,
                                  nsIAppShell *aAppShell = nsnull,
                                  nsIToolkit *aToolkit = nsnull,
                                  nsWidgetInitData *aInitData = nsnull);
   NS_IMETHOD              Create(nsNativeWidget aNativeParent,
-                                 const nsRect &aRect,
+                                 const nsIntRect &aRect,
                                  EVENT_CALLBACK aHandleEventFunction,
                                  nsIDeviceContext *aContext,
                                  nsIAppShell *aAppShell = nsnull,
@@ -277,7 +277,7 @@ public:
    // Create(nsNativeWidget...)
 
   virtual nsresult        StandardCreate(nsIWidget *aParent,
-                              const nsRect &aRect,
+                              const nsIntRect &aRect,
                               EVENT_CALLBACK aHandleEventFunction,
                               nsIDeviceContext *aContext,
                               nsIAppShell *aAppShell,
@@ -304,19 +304,19 @@ public:
   NS_IMETHOD              Enable(PRBool aState);
   NS_IMETHOD              IsEnabled(PRBool *aState);
   NS_IMETHOD              SetFocus(PRBool aRaise);
-  NS_IMETHOD              SetBounds(const nsRect &aRect);
-  NS_IMETHOD              GetBounds(nsRect &aRect);
+  NS_IMETHOD              SetBounds(const nsIntRect &aRect);
+  NS_IMETHOD              GetBounds(nsIntRect &aRect);
 
   NS_IMETHOD              Invalidate(PRBool aIsSynchronous);
-  NS_IMETHOD              Invalidate(const nsRect &aRect,PRBool aIsSynchronous);
+  NS_IMETHOD              Invalidate(const nsIntRect &aRect, PRBool aIsSynchronous);
   NS_IMETHOD              InvalidateRegion(const nsIRegion *aRegion, PRBool aIsSynchronous);
   NS_IMETHOD              Validate();
 
   virtual void*           GetNativeData(PRUint32 aDataType);
   NS_IMETHOD              SetColorMap(nsColorMap *aColorMap);
-  NS_IMETHOD              Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *aClipRect);
-  NS_IMETHOD              WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect);
-  NS_IMETHOD              ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect);
+  NS_IMETHOD              Scroll(PRInt32 aDx, PRInt32 aDy, nsIntRect *aClipRect);
+  NS_IMETHOD              WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect);
+  NS_IMETHOD              ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect);
   NS_IMETHOD              BeginResizingChildren(void);
   NS_IMETHOD              EndResizingChildren(void);
   virtual PRBool          ShowsResizeIndicator(nsIntRect* aResizerRect);
@@ -328,9 +328,9 @@ public:
   NS_IMETHOD              Update();
 
   virtual void      ConvertToDeviceCoordinates(nscoord &aX, nscoord &aY);
-  void              LocalToWindowCoordinate(nsPoint& aPoint)            { ConvertToDeviceCoordinates(aPoint.x, aPoint.y); }
+  void              LocalToWindowCoordinate(nsIntPoint& aPoint)         { ConvertToDeviceCoordinates(aPoint.x, aPoint.y); }
   void              LocalToWindowCoordinate(nscoord& aX, nscoord& aY)   { ConvertToDeviceCoordinates(aX, aY); }
-  void              LocalToWindowCoordinate(nsRect& aRect)              { ConvertToDeviceCoordinates(aRect.x, aRect.y); }
+  void              LocalToWindowCoordinate(nsIntRect& aRect)           { ConvertToDeviceCoordinates(aRect.x, aRect.y); }
 
   NS_IMETHOD        SetMenuBar(void* aMenuBar);
   NS_IMETHOD        ShowMenuBar(PRBool aShow);
diff --git a/widget/src/cocoa/nsChildView.mm b/widget/src/cocoa/nsChildView.mm
index eeb4c2b86998..222925ceca80 100644
--- a/widget/src/cocoa/nsChildView.mm
+++ b/widget/src/cocoa/nsChildView.mm
@@ -139,7 +139,7 @@ nsIWidget         * gRollupWidget   = nsnull;
 - (id)initWithFrame:(NSRect)inFrame geckoChild:(nsChildView*)inChild;
 
 // sends gecko an ime composition event
-- (nsRect) sendCompositionEvent:(PRInt32)aEventType;
+- (nsIntRect) sendCompositionEvent:(PRInt32)aEventType;
 
 // sends gecko an ime text event
 - (void) sendTextEvent:(PRUnichar*) aBuffer 
@@ -208,7 +208,7 @@ nsIWidget         * gRollupWidget   = nsnull;
 
 
 static inline void
-GeckoRectToNSRect(const nsRect & inGeckoRect, NSRect & outCocoaRect)
+GeckoRectToNSRect(const nsIntRect & inGeckoRect, NSRect & outCocoaRect)
 {
   outCocoaRect.origin.x = inGeckoRect.x;
   outCocoaRect.origin.y = inGeckoRect.y;
@@ -217,12 +217,12 @@ GeckoRectToNSRect(const nsRect & inGeckoRect, NSRect & outCocoaRect)
 }
 
 static inline void
-NSRectToGeckoRect(const NSRect & inCocoaRect, nsRect & outGeckoRect)
+NSRectToGeckoRect(const NSRect & inCocoaRect, nsIntRect & outGeckoRect)
 {
-  outGeckoRect.x = static_cast<nscoord>(inCocoaRect.origin.x);
-  outGeckoRect.y = static_cast<nscoord>(inCocoaRect.origin.y);
-  outGeckoRect.width = static_cast<nscoord>(inCocoaRect.size.width);
-  outGeckoRect.height = static_cast<nscoord>(inCocoaRect.size.height);
+  outGeckoRect.x = NSToIntFloor(inCocoaRect.origin.x);
+  outGeckoRect.y = NSToIntFloor(inCocoaRect.origin.y);
+  outGeckoRect.width = NSToIntCeil(inCocoaRect.size.width);
+  outGeckoRect.height = NSToIntCeil(inCocoaRect.size.height);
 }
 
 
@@ -452,7 +452,7 @@ NS_IMPL_ISUPPORTS_INHERITED1(nsChildView, nsBaseWidget, nsIPluginWidget)
 // Utility method for implementing both Create(nsIWidget ...)
 // and Create(nsNativeWidget...)
 nsresult nsChildView::StandardCreate(nsIWidget *aParent,
-                      const nsRect &aRect,
+                      const nsIntRect &aRect,
                       EVENT_CALLBACK aHandleEventFunction,
                       nsIDeviceContext *aContext,
                       nsIAppShell *aAppShell,
@@ -582,7 +582,7 @@ void nsChildView::TearDownView()
 
 // create a nsChildView
 NS_IMETHODIMP nsChildView::Create(nsIWidget *aParent,
-                      const nsRect &aRect,
+                      const nsIntRect &aRect,
                       EVENT_CALLBACK aHandleEventFunction,
                       nsIDeviceContext *aContext,
                       nsIAppShell *aAppShell,
@@ -596,7 +596,7 @@ NS_IMETHODIMP nsChildView::Create(nsIWidget *aParent,
 
 // Creates a main nsChildView using a native widget (an NSView)
 NS_IMETHODIMP nsChildView::Create(nsNativeWidget aNativeParent,
-                      const nsRect &aRect,
+                      const nsIntRect &aRect,
                       EVENT_CALLBACK aHandleEventFunction,
                       nsIDeviceContext *aContext,
                       nsIAppShell *aAppShell,
@@ -990,14 +990,14 @@ NS_IMETHODIMP nsChildView::SetCursor(imgIContainer* aCursor,
 
 
 // Get this component dimension
-NS_IMETHODIMP nsChildView::GetBounds(nsRect &aRect)
+NS_IMETHODIMP nsChildView::GetBounds(nsIntRect &aRect)
 {
   aRect = mBounds;
   return NS_OK;
 }
 
 
-NS_IMETHODIMP nsChildView::SetBounds(const nsRect &aRect)
+NS_IMETHODIMP nsChildView::SetBounds(const nsIntRect &aRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
@@ -1526,7 +1526,7 @@ NS_IMETHODIMP nsChildView::Invalidate(PRBool aIsSynchronous)
 
 
 // Invalidate this component's visible area
-NS_IMETHODIMP nsChildView::Invalidate(const nsRect &aRect, PRBool aIsSynchronous)
+NS_IMETHODIMP nsChildView::Invalidate(const nsIntRect &aRect, PRBool aIsSynchronous)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
@@ -1576,7 +1576,7 @@ NS_IMETHODIMP nsChildView::InvalidateRegion(const nsIRegion *aRegion, PRBool aIs
 
   // FIXME rewrite to use a Cocoa region when nsIRegion isn't a QD Region
   NSRect r;
-  nsRect bounds;
+  nsIntRect bounds;
   nsIRegion* region = const_cast<nsIRegion*>(aRegion);     // ugh. this method should be const
   region->GetBoundingBox(&bounds.x, &bounds.y, &bounds.width, &bounds.height);
   GeckoRectToNSRect(bounds, r);
@@ -1626,7 +1626,7 @@ NS_IMETHODIMP nsChildView::Update()
 
 // Scroll the bits of a view and its children
 // FIXME: I'm sure the invalidating can be optimized, just no time now.
-NS_IMETHODIMP nsChildView::Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *aClipRect)
+NS_IMETHODIMP nsChildView::Scroll(PRInt32 aDx, PRInt32 aDy, nsIntRect *aClipRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
@@ -1648,7 +1648,7 @@ NS_IMETHODIMP nsChildView::Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *aClipRect)
     // over repainting.  We can scroll like a bat out of hell
     // by not wasting time invalidating the widgets, since it's
     // completely unnecessary to do so.
-    nsRect bounds;
+    nsIntRect bounds;
     kid->GetBounds(bounds);
     kid->Resize(bounds.x + aDx, bounds.y + aDy, bounds.width, bounds.height, PR_FALSE);
   }
@@ -1867,11 +1867,11 @@ NS_IMETHODIMP nsChildView::CalcOffset(PRInt32 &aX,PRInt32 &aY)
 PRBool nsChildView::PointInWidget(Point aThePoint)
 {
   // get the origin in local coordinates
-  nsPoint widgetOrigin(0, 0);
+  nsIntPoint widgetOrigin(0, 0);
   LocalToWindowCoordinate(widgetOrigin);
 
   // get rectangle relatively to the parent
-  nsRect widgetRect;
+  nsIntRect widgetRect;
   GetBounds(widgetRect);
 
   // convert the topLeft corner to local coordinates
@@ -1887,7 +1887,7 @@ PRBool nsChildView::PointInWidget(Point aThePoint)
 //    Convert the given rect to global coordinates.
 //    @param aLocalRect  -- rect in local coordinates of this widget
 //    @param aGlobalRect -- |aLocalRect| in global coordinates
-NS_IMETHODIMP nsChildView::WidgetToScreen(const nsRect& aLocalRect, nsRect& aGlobalRect)
+NS_IMETHODIMP nsChildView::WidgetToScreen(const nsIntRect& aLocalRect, nsIntRect& aGlobalRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
@@ -1927,7 +1927,7 @@ NS_IMETHODIMP nsChildView::WidgetToScreen(const nsRect& aLocalRect, nsRect& aGlo
 //    Convert the given rect to local coordinates.
 //    @param aGlobalRect  -- rect in screen coordinates 
 //    @param aLocalRect -- |aGlobalRect| in coordinates of this widget
-NS_IMETHODIMP nsChildView::ScreenToWidget(const nsRect& aGlobalRect, nsRect& aLocalRect)
+NS_IMETHODIMP nsChildView::ScreenToWidget(const nsIntRect& aGlobalRect, nsIntRect& aLocalRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
@@ -2743,7 +2743,7 @@ NSEvent* gLastDragEvent = nil;
 
   CGContextRef cgContext = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
 
-  nsRect geckoBounds;
+  nsIntRect geckoBounds;
   mGeckoChild->GetBounds(geckoBounds);
 
   NSRect bounds = [self bounds];
@@ -2787,7 +2787,7 @@ NSEvent* gLastDragEvent = nil;
   targetContext->Clip();
   
   // bounding box of the dirty area
-  nsRect fullRect;
+  nsIntRect fullRect;
   NSRectToGeckoRect(aRect, fullRect);
 
   nsPaintEvent paintEvent(PR_TRUE, NS_PAINT, mGeckoChild);
@@ -4696,14 +4696,14 @@ GetUSLayoutCharFromKeyTranslate(UInt32 aKeyCode, UInt32 aModifiers)
 }
 
 
-- (nsRect)sendCompositionEvent:(PRInt32) aEventType
+- (nsIntRect)sendCompositionEvent:(PRInt32) aEventType
 {
 #ifdef DEBUG_IME
   NSLog(@"****in sendCompositionEvent; type = %d", aEventType);
 #endif
 
   if (!mGeckoChild)
-    return nsRect(0, 0, 0, 0);
+    return nsIntRect(0, 0, 0, 0);
 
   // static void init_composition_event( *aEvent, int aType)
   nsCompositionEvent event(PR_TRUE, aEventType, mGeckoChild);
@@ -5068,7 +5068,7 @@ GetUSLayoutCharFromKeyTranslate(UInt32 aKeyCode, UInt32 aModifiers)
   if (!mGeckoChild || theRange.location == NSNotFound)
     return rect;
 
-  nsRect r;
+  nsIntRect r;
   PRBool useCaretRect = theRange.length == 0;
   if (!useCaretRect) {
     nsQueryContentEvent charRect(PR_TRUE, NS_QUERY_CHARACTER_RECT, mGeckoChild);
diff --git a/widget/src/cocoa/nsCocoaUtils.h b/widget/src/cocoa/nsCocoaUtils.h
index 8c2bca2577c9..5a177d311f49 100644
--- a/widget/src/cocoa/nsCocoaUtils.h
+++ b/widget/src/cocoa/nsCocoaUtils.h
@@ -115,10 +115,10 @@ class nsCocoaUtils
   // (NSRect) contain an origin (x,y) in a coordinate system with (0,0)
   // in the bottom-left of the primary screen. Both nsRect and NSRect
   // contain width/height info, with no difference in their use.
-  static NSRect GeckoRectToCocoaRect(const nsRect &geckoRect);
+  static NSRect GeckoRectToCocoaRect(const nsIntRect &geckoRect);
   
   // See explanation for geckoRectToCocoaRect, guess what this does...
-  static nsRect CocoaRectToGeckoRect(const NSRect &cocoaRect);
+  static nsIntRect CocoaRectToGeckoRect(const NSRect &cocoaRect);
   
   // Gives the location for the event in screen coordinates. Do not call this
   // unless the window the event was originally targeted at is still alive!
diff --git a/widget/src/cocoa/nsCocoaUtils.mm b/widget/src/cocoa/nsCocoaUtils.mm
index 7f7700d473db..0e32a65e2fc8 100644
--- a/widget/src/cocoa/nsCocoaUtils.mm
+++ b/widget/src/cocoa/nsCocoaUtils.mm
@@ -70,7 +70,7 @@ float nsCocoaUtils::FlippedScreenY(float y)
 }
 
 
-NSRect nsCocoaUtils::GeckoRectToCocoaRect(const nsRect &geckoRect)
+NSRect nsCocoaUtils::GeckoRectToCocoaRect(const nsIntRect &geckoRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_RETURN;
 
@@ -85,15 +85,17 @@ NSRect nsCocoaUtils::GeckoRectToCocoaRect(const nsRect &geckoRect)
 }
 
 
-nsRect nsCocoaUtils::CocoaRectToGeckoRect(const NSRect &cocoaRect)
+nsIntRect nsCocoaUtils::CocoaRectToGeckoRect(const NSRect &cocoaRect)
 {
   // We only need to change the Y coordinate by starting with the primary screen
   // height and subtracting both the cocoa y origin and the height of the
   // cocoa rect.
-  return nsRect((nscoord)cocoaRect.origin.x,
-                (nscoord)(MenuBarScreenHeight() - (cocoaRect.origin.y + cocoaRect.size.height)),
-                (nscoord)cocoaRect.size.width,
-                (nscoord)cocoaRect.size.height);
+  nsIntRect rect;
+  rect.x = NSToIntFloor(cocoaRect.origin.x);
+  rect.y = NSToIntFloor(MenuBarScreenHeight() - (cocoaRect.origin.y + cocoaRect.size.height));
+  rect.width = NSToIntCeil(cocoaRect.origin.x + cocoaRect.size.width) - rect.x;
+  rect.height = NSToIntCeil(MenuBarScreenHeight() - cocoaRect.origin.y) - rect.y;
+  return rect;
 }
 
 
diff --git a/widget/src/cocoa/nsCocoaWindow.h b/widget/src/cocoa/nsCocoaWindow.h
index 8c59903d7b36..5d0c27f6122f 100644
--- a/widget/src/cocoa/nsCocoaWindow.h
+++ b/widget/src/cocoa/nsCocoaWindow.h
@@ -203,7 +203,7 @@ public:
     NS_DECL_NSPIWIDGETCOCOA
       
     NS_IMETHOD              Create(nsNativeWidget aParent,
-                                   const nsRect &aRect,
+                                   const nsIntRect &aRect,
                                    EVENT_CALLBACK aHandleEventFunction,
                                    nsIDeviceContext *aContext,
                                    nsIAppShell *aAppShell = nsnull,
@@ -211,7 +211,7 @@ public:
                                    nsWidgetInitData *aInitData = nsnull);
 
     NS_IMETHOD              Create(nsIWidget* aParent,
-                                   const nsRect &aRect,
+                                   const nsIntRect &aRect,
                                    EVENT_CALLBACK aHandleEventFunction,
                                    nsIDeviceContext *aContext,
                                    nsIAppShell *aAppShell = nsnull,
@@ -223,7 +223,7 @@ public:
      // Create(nsNativeWidget...)
 
     virtual nsresult        StandardCreate(nsIWidget *aParent,
-                                    const nsRect &aRect,
+                                    const nsIntRect &aRect,
                                     EVENT_CALLBACK aHandleEventFunction,
                                     nsIDeviceContext *aContext,
                                     nsIAppShell *aAppShell,
@@ -242,8 +242,8 @@ public:
     NS_IMETHOD              SetMenuBar(void* aMenuBar);
     virtual nsMenuBarX*     GetMenuBar();
     NS_IMETHOD              ShowMenuBar(PRBool aShow);
-    NS_IMETHOD WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect);
-    NS_IMETHOD ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect);
+    NS_IMETHOD WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect);
+    NS_IMETHOD ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect);
     
     virtual void* GetNativeData(PRUint32 aDataType) ;
 
@@ -256,16 +256,16 @@ public:
 
     NS_IMETHOD              Resize(PRInt32 aWidth,PRInt32 aHeight, PRBool aRepaint);
     NS_IMETHOD              Resize(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRInt32 aHeight, PRBool aRepaint);
-    NS_IMETHOD              GetScreenBounds(nsRect &aRect);
+    NS_IMETHOD              GetScreenBounds(nsIntRect &aRect);
     virtual PRBool          OnPaint(nsPaintEvent &event);
     void                    ReportSizeEvent(NSRect *overrideRect = nsnull);
 
     NS_IMETHOD              SetTitle(const nsAString& aTitle);
 
-    NS_IMETHOD Invalidate(const nsRect & aRect, PRBool aIsSynchronous);
+    NS_IMETHOD Invalidate(const nsIntRect &aRect, PRBool aIsSynchronous);
     NS_IMETHOD Invalidate(PRBool aIsSynchronous);
     NS_IMETHOD Update();
-    NS_IMETHOD Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *alCipRect) { return NS_OK; }
+    NS_IMETHOD Scroll(PRInt32 aDx, PRInt32 aDy, nsIntRect *alCipRect) { return NS_OK; }
     NS_IMETHOD SetColorMap(nsColorMap *aColorMap) { return NS_OK; }
     NS_IMETHOD BeginResizingChildren(void) { return NS_OK; }
     NS_IMETHOD EndResizingChildren(void) { return NS_OK; }
diff --git a/widget/src/cocoa/nsCocoaWindow.mm b/widget/src/cocoa/nsCocoaWindow.mm
index c6fe916558d0..ca0fa34c0adb 100644
--- a/widget/src/cocoa/nsCocoaWindow.mm
+++ b/widget/src/cocoa/nsCocoaWindow.mm
@@ -180,7 +180,7 @@ static bool WindowSizeAllowed(PRInt32 aWidth, PRInt32 aHeight)
 // Utility method for implementing both Create(nsIWidget ...) and
 // Create(nsNativeWidget...)
 nsresult nsCocoaWindow::StandardCreate(nsIWidget *aParent,
-                        const nsRect &aRect,
+                        const nsIntRect &aRect,
                         EVENT_CALLBACK aHandleEventFunction,
                         nsIDeviceContext *aContext,
                         nsIAppShell *aAppShell,
@@ -406,7 +406,7 @@ nsresult nsCocoaWindow::StandardCreate(nsIWidget *aParent,
 
 // Create a nsCocoaWindow using a native window provided by the application
 NS_IMETHODIMP nsCocoaWindow::Create(nsNativeWidget aNativeWindow,
-                      const nsRect &aRect,
+                      const nsIntRect &aRect,
                       EVENT_CALLBACK aHandleEventFunction,
                       nsIDeviceContext *aContext,
                       nsIAppShell *aAppShell,
@@ -419,7 +419,7 @@ NS_IMETHODIMP nsCocoaWindow::Create(nsNativeWidget aNativeWindow,
 
 
 NS_IMETHODIMP nsCocoaWindow::Create(nsIWidget* aParent,
-                      const nsRect &aRect,
+                      const nsIntRect &aRect,
                       EVENT_CALLBACK aHandleEventFunction,
                       nsIDeviceContext *aContext,
                       nsIAppShell *aAppShell,
@@ -938,14 +938,14 @@ NS_IMETHODIMP nsCocoaWindow::Resize(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRIn
   if (!WindowSizeAllowed(aWidth, aHeight))
     return NS_ERROR_FAILURE;
 
-  nsRect windowBounds(nsCocoaUtils::CocoaRectToGeckoRect([mWindow frame]));
+  nsIntRect windowBounds(nsCocoaUtils::CocoaRectToGeckoRect([mWindow frame]));
   BOOL isMoving = (windowBounds.x != aX || windowBounds.y != aY);
   BOOL isResizing = (windowBounds.width != aWidth || windowBounds.height != aHeight);
 
   if (IsResizing() || !mWindow || (!isMoving && !isResizing))
     return NS_OK;
 
-  nsRect geckoRect(aX, aY, aWidth, aHeight);
+  nsIntRect geckoRect(aX, aY, aWidth, aHeight);
   NSRect newFrame = nsCocoaUtils::GeckoRectToCocoaRect(geckoRect);
 
   // We have to report the size event -first-, to make sure that content
@@ -985,22 +985,18 @@ NS_IMETHODIMP nsCocoaWindow::Resize(PRInt32 aWidth, PRInt32 aHeight, PRBool aRep
   if (!WindowSizeAllowed(aWidth, aHeight))
     return NS_ERROR_FAILURE;
 
-  nsRect windowBounds(nsCocoaUtils::CocoaRectToGeckoRect([mWindow frame]));
+  nsIntRect windowBounds(nsCocoaUtils::CocoaRectToGeckoRect([mWindow frame]));
   return Resize(windowBounds.x, windowBounds.y, aWidth, aHeight, aRepaint);
 
   NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
 }
 
 
-NS_IMETHODIMP nsCocoaWindow::GetScreenBounds(nsRect &aRect)
+NS_IMETHODIMP nsCocoaWindow::GetScreenBounds(nsIntRect &aRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
-  nsRect windowFrame = nsCocoaUtils::CocoaRectToGeckoRect([mWindow frame]);
-  aRect.x = windowFrame.x;
-  aRect.y = windowFrame.y;
-  aRect.width = windowFrame.width;
-  aRect.height = windowFrame.height;
+  aRect = nsCocoaUtils::CocoaRectToGeckoRect([mWindow frame]);
   // printf("GetScreenBounds: output: %d,%d,%d,%d\n", aRect.x, aRect.y, aRect.width, aRect.height);
   return NS_OK;
 
@@ -1028,7 +1024,7 @@ NS_IMETHODIMP nsCocoaWindow::SetTitle(const nsAString& aTitle)
 }
 
 
-NS_IMETHODIMP nsCocoaWindow::Invalidate(const nsRect & aRect, PRBool aIsSynchronous)
+NS_IMETHODIMP nsCocoaWindow::Invalidate(const nsIntRect & aRect, PRBool aIsSynchronous)
 {
   if (mPopupContentView)
     return mPopupContentView->Invalidate(aRect, aIsSynchronous);
@@ -1226,11 +1222,11 @@ NS_IMETHODIMP nsCocoaWindow::ShowMenuBar(PRBool aShow)
 }
 
 
-NS_IMETHODIMP nsCocoaWindow::WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect)
+NS_IMETHODIMP nsCocoaWindow::WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
-  nsRect r = nsCocoaUtils::CocoaRectToGeckoRect([mWindow contentRectForFrameRect:[mWindow frame]]);
+  nsIntRect r(nsCocoaUtils::CocoaRectToGeckoRect([mWindow contentRectForFrameRect:[mWindow frame]]));
 
   aNewRect.x = r.x + aOldRect.x;
   aNewRect.y = r.y + aOldRect.y;
@@ -1243,11 +1239,11 @@ NS_IMETHODIMP nsCocoaWindow::WidgetToScreen(const nsRect& aOldRect, nsRect& aNew
 }
 
 
-NS_IMETHODIMP nsCocoaWindow::ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect)
+NS_IMETHODIMP nsCocoaWindow::ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
-  nsRect r = nsCocoaUtils::CocoaRectToGeckoRect([mWindow contentRectForFrameRect:[mWindow frame]]);
+  nsIntRect r(nsCocoaUtils::CocoaRectToGeckoRect([mWindow contentRectForFrameRect:[mWindow frame]]));
 
   aNewRect.x = aOldRect.x - r.x;
   aNewRect.y = aOldRect.y - r.y;
@@ -1546,7 +1542,7 @@ NS_IMETHODIMP nsCocoaWindow::EndSecureKeyboardInput()
 {
   // Dispatch the move event to Gecko
   nsGUIEvent guiEvent(PR_TRUE, NS_MOVE, mGeckoWindow);
-  nsRect rect;
+  nsIntRect rect;
   mGeckoWindow->GetScreenBounds(rect);
   guiEvent.refPoint.x = rect.x;
   guiEvent.refPoint.y = rect.y;
diff --git a/widget/src/cocoa/nsDragService.h b/widget/src/cocoa/nsDragService.h
index 4fe2cf9a696d..3304394f93eb 100644
--- a/widget/src/cocoa/nsDragService.h
+++ b/widget/src/cocoa/nsDragService.h
@@ -67,7 +67,7 @@ public:
 private:
 
   NSImage* ConstructDragImage(nsIDOMNode* aDOMNode,
-                              nsRect* aDragRect,
+                              nsIntRect* aDragRect,
                               nsIScriptableRegion* aRegion);
 
   nsCOMPtr<nsISupportsArray> mDataItems; // only valid for a drag started within gecko
diff --git a/widget/src/cocoa/nsDragService.mm b/widget/src/cocoa/nsDragService.mm
index 90b74510fb4d..43277a01fde1 100644
--- a/widget/src/cocoa/nsDragService.mm
+++ b/widget/src/cocoa/nsDragService.mm
@@ -160,7 +160,7 @@ static nsresult SetUpDragClipboard(nsISupportsArray* aTransferableArray)
 
 NSImage*
 nsDragService::ConstructDragImage(nsIDOMNode* aDOMNode,
-                                  nsRect* aDragRect,
+                                  nsIntRect* aDragRect,
                                   nsIScriptableRegion* aRegion)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
@@ -264,7 +264,7 @@ nsDragService::InvokeDragSession(nsIDOMNode* aDOMNode, nsISupportsArray* aTransf
   if (NS_FAILED(SetUpDragClipboard(aTransferableArray)))
     return NS_ERROR_FAILURE;
 
-  nsRect dragRect(0, 0, 20, 20);
+  nsIntRect dragRect(0, 0, 20, 20);
   NSImage* image = ConstructDragImage(aDOMNode, &dragRect, aDragRgn);
   if (!image) {
     // if no image was returned, just draw a rectangle
diff --git a/widget/src/cocoa/nsNativeThemeCocoa.h b/widget/src/cocoa/nsNativeThemeCocoa.h
index 98d229f1a088..5397af0ca839 100644
--- a/widget/src/cocoa/nsNativeThemeCocoa.h
+++ b/widget/src/cocoa/nsNativeThemeCocoa.h
@@ -68,19 +68,19 @@ public:
   NS_IMETHOD GetWidgetBorder(nsIDeviceContext* aContext, 
                              nsIFrame* aFrame,
                              PRUint8 aWidgetType,
-                             nsMargin* aResult);
+                             nsIntMargin* aResult);
 
   virtual PRBool GetWidgetPadding(nsIDeviceContext* aContext,
                                   nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsMargin* aResult);
+                                  nsIntMargin* aResult);
 
   virtual PRBool GetWidgetOverflow(nsIDeviceContext* aContext, nsIFrame* aFrame,
                                    PRUint8 aWidgetType, nsRect* aOverflowRect);
 
   NS_IMETHOD GetMinimumWidgetSize(nsIRenderingContext* aContext, nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsSize* aResult, PRBool* aIsOverridable);
+                                  nsIntSize* aResult, PRBool* aIsOverridable);
   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, PRUint8 aWidgetType, 
                                 nsIAtom* aAttribute, PRBool* aShouldRepaint);
   NS_IMETHOD ThemeChanged();
diff --git a/widget/src/cocoa/nsNativeThemeCocoa.mm b/widget/src/cocoa/nsNativeThemeCocoa.mm
index e27aff539834..48b676c226d2 100644
--- a/widget/src/cocoa/nsNativeThemeCocoa.mm
+++ b/widget/src/cocoa/nsNativeThemeCocoa.mm
@@ -1498,7 +1498,7 @@ NS_IMETHODIMP
 nsNativeThemeCocoa::GetWidgetBorder(nsIDeviceContext* aContext, 
                                     nsIFrame* aFrame,
                                     PRUint8 aWidgetType,
-                                    nsMargin* aResult)
+                                    nsIntMargin* aResult)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
@@ -1586,7 +1586,7 @@ PRBool
 nsNativeThemeCocoa::GetWidgetPadding(nsIDeviceContext* aContext, 
                                      nsIFrame* aFrame,
                                      PRUint8 aWidgetType,
-                                     nsMargin* aResult)
+                                     nsIntMargin* aResult)
 {
   // We don't want CSS padding being used for certain widgets.
   // See bug 381639 for an example of why.
@@ -1643,7 +1643,7 @@ NS_IMETHODIMP
 nsNativeThemeCocoa::GetMinimumWidgetSize(nsIRenderingContext* aContext,
                                          nsIFrame* aFrame,
                                          PRUint8 aWidgetType,
-                                         nsSize* aResult,
+                                         nsIntSize* aResult,
                                          PRBool* aIsOverridable)
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
diff --git a/widget/src/cocoa/nsScreenCocoa.mm b/widget/src/cocoa/nsScreenCocoa.mm
index 34540dc3a673..aca71d520292 100644
--- a/widget/src/cocoa/nsScreenCocoa.mm
+++ b/widget/src/cocoa/nsScreenCocoa.mm
@@ -63,7 +63,7 @@ nsScreenCocoa::~nsScreenCocoa ()
 NS_IMETHODIMP
 nsScreenCocoa::GetRect(PRInt32 *outX, PRInt32 *outY, PRInt32 *outWidth, PRInt32 *outHeight)
 {
-  nsRect r = nsCocoaUtils::CocoaRectToGeckoRect([mScreen frame]);
+  nsIntRect r(nsCocoaUtils::CocoaRectToGeckoRect([mScreen frame]));
 
   *outX = r.x;
   *outY = r.y;
@@ -76,7 +76,7 @@ nsScreenCocoa::GetRect(PRInt32 *outX, PRInt32 *outY, PRInt32 *outWidth, PRInt32
 NS_IMETHODIMP
 nsScreenCocoa::GetAvailRect(PRInt32 *outX, PRInt32 *outY, PRInt32 *outWidth, PRInt32 *outHeight)
 {
-  nsRect r = nsCocoaUtils::CocoaRectToGeckoRect([mScreen visibleFrame]);
+  nsIntRect r(nsCocoaUtils::CocoaRectToGeckoRect([mScreen visibleFrame]));
 
   *outX = r.x;
   *outY = r.y;
diff --git a/widget/src/cocoa/nsScreenManagerCocoa.mm b/widget/src/cocoa/nsScreenManagerCocoa.mm
index a6252551751c..3e9f14835397 100644
--- a/widget/src/cocoa/nsScreenManagerCocoa.mm
+++ b/widget/src/cocoa/nsScreenManagerCocoa.mm
@@ -76,7 +76,7 @@ nsScreenManagerCocoa::ScreenForRect (PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRI
     NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NSRESULT;
 
     NSEnumerator *screenEnum = [[NSScreen screens] objectEnumerator];
-    NSRect inRect = nsCocoaUtils::GeckoRectToCocoaRect(nsRect(aX, aY, aWidth, aHeight));
+    NSRect inRect(nsCocoaUtils::GeckoRectToCocoaRect(nsIntRect(aX, aY, aWidth, aHeight)));
     NSScreen *screenWindowIsOn = [NSScreen mainScreen];
     float greatestArea = 0;
 
diff --git a/widget/src/gtk2/nsCommonWidget.cpp b/widget/src/gtk2/nsCommonWidget.cpp
index a90354ca4b58..833ee543e375 100644
--- a/widget/src/gtk2/nsCommonWidget.cpp
+++ b/widget/src/gtk2/nsCommonWidget.cpp
@@ -128,7 +128,7 @@ nsCommonWidget::DispatchDeactivateEvent(void)
 }
 
 void
-nsCommonWidget::DispatchResizeEvent(nsRect &aRect, nsEventStatus &aStatus)
+nsCommonWidget::DispatchResizeEvent(nsIntRect &aRect, nsEventStatus &aStatus)
 {
     nsSizeEvent event(PR_TRUE, NS_SIZE, this);
 
@@ -204,7 +204,7 @@ nsCommonWidget::Show(PRBool aState)
 NS_IMETHODIMP
 nsCommonWidget::Resize(PRInt32 aWidth, PRInt32 aHeight, PRBool aRepaint)
 {
-    mBounds.SizeTo(GetSafeWindowSize(nsSize(aWidth, aHeight)));
+    mBounds.SizeTo(GetSafeWindowSize(nsIntSize(aWidth, aHeight)));
 
     if (!mCreated)
         return NS_OK;
@@ -263,7 +263,7 @@ nsCommonWidget::Resize(PRInt32 aWidth, PRInt32 aHeight, PRBool aRepaint)
 
     // synthesize a resize event if this isn't a toplevel
     if (mIsTopLevel || mListenForResizes) {
-        nsRect rect(mBounds.x, mBounds.y, aWidth, aHeight);
+        nsIntRect rect(mBounds.x, mBounds.y, aWidth, aHeight);
         nsEventStatus status;
         DispatchResizeEvent(rect, status);
     }
@@ -277,7 +277,7 @@ nsCommonWidget::Resize(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRInt32 aHeight,
 {
     mBounds.x = aX;
     mBounds.y = aY;
-    mBounds.SizeTo(GetSafeWindowSize(nsSize(aWidth, aHeight)));
+    mBounds.SizeTo(GetSafeWindowSize(nsIntSize(aWidth, aHeight)));
 
     mPlaced = PR_TRUE;
 
@@ -328,7 +328,7 @@ nsCommonWidget::Resize(PRInt32 aX, PRInt32 aY, PRInt32 aWidth, PRInt32 aHeight,
 
     if (mIsTopLevel || mListenForResizes) {
         // synthesize a resize event
-        nsRect rect(aX, aY, aWidth, aHeight);
+        nsIntRect rect(aX, aY, aWidth, aHeight);
         nsEventStatus status;
         DispatchResizeEvent(rect, status);
     }
diff --git a/widget/src/gtk2/nsCommonWidget.h b/widget/src/gtk2/nsCommonWidget.h
index 15a1efb849d7..459695e8319f 100644
--- a/widget/src/gtk2/nsCommonWidget.h
+++ b/widget/src/gtk2/nsCommonWidget.h
@@ -85,7 +85,7 @@ public:
     void DispatchLostFocusEvent(void);
     void DispatchActivateEvent(void);
     void DispatchDeactivateEvent(void);
-    void DispatchResizeEvent(nsRect &aRect, nsEventStatus &aStatus);
+    void DispatchResizeEvent(nsIntRect &aRect, nsEventStatus &aStatus);
 
     NS_IMETHOD DispatchEvent(nsGUIEvent *aEvent, nsEventStatus &aStatus);
 
@@ -102,7 +102,7 @@ public:
 
     virtual void NativeShow  (PRBool  aAction) = 0;
 
-    virtual nsSize GetSafeWindowSize(nsSize aSize) = 0;
+    virtual nsIntSize GetSafeWindowSize(const nsIntSize &aSize) = 0;
 
     // Some of the nsIWidget methods
     NS_IMETHOD         Show             (PRBool aState);
diff --git a/widget/src/gtk2/nsDragService.cpp b/widget/src/gtk2/nsDragService.cpp
index c09809dea8fb..52cce3734423 100644
--- a/widget/src/gtk2/nsDragService.cpp
+++ b/widget/src/gtk2/nsDragService.cpp
@@ -208,7 +208,7 @@ nsDragService::InvokeDragSession(nsIDOMNode *aDOMNode,
                                                  &event);
 
         PRBool needsFallbackIcon = PR_FALSE;
-        nsRect dragRect;
+        nsIntRect dragRect;
         nsPresContext* pc;
         nsRefPtr<gfxASurface> surface;
         if (mHasImage || mSelection) {
@@ -220,8 +220,8 @@ nsDragService::InvokeDragSession(nsIDOMNode *aDOMNode,
           PRInt32 sx = mScreenX, sy = mScreenY;
           ConvertToUnscaledDevPixels(pc, &sx, &sy);
 
-          PRInt32 offsetX = sx - NSToIntRound(dragRect.x);
-          PRInt32 offsetY = sy - NSToIntRound(dragRect.y);
+          PRInt32 offsetX = sx - dragRect.x;
+          PRInt32 offsetY = sy - dragRect.y;
           if (!SetAlphaPixmap(surface, context, offsetX, offsetY, dragRect)) {
             GdkPixbuf* dragPixbuf =
               nsImageToPixbuf::SurfaceToPixbuf(surface, dragRect.width, dragRect.height);
@@ -248,7 +248,7 @@ nsDragService::SetAlphaPixmap(gfxASurface *aSurface,
                                  GdkDragContext *aContext,
                                  PRInt32 aXOffset,
                                  PRInt32 aYOffset,
-                                 const nsRect& dragRect)
+                                 const nsIntRect& dragRect)
 {
     GdkScreen* screen = gtk_widget_get_screen(mHiddenWidget);
 
diff --git a/widget/src/gtk2/nsDragService.h b/widget/src/gtk2/nsDragService.h
index f20c67184ab0..aa86e122cae6 100644
--- a/widget/src/gtk2/nsDragService.h
+++ b/widget/src/gtk2/nsDragService.h
@@ -144,11 +144,11 @@ private:
 
     // attempts to create a semi-transparent drag image. Returns TRUE if
     // successful, FALSE if not
-    PRBool SetAlphaPixmap(gfxASurface    *aPixbuf,
-                          GdkDragContext *aContext,
-                          PRInt32         aXOffset,
-                          PRInt32         aYOffset,
-                          const nsRect&   dragRect);
+    PRBool SetAlphaPixmap(gfxASurface     *aPixbuf,
+                          GdkDragContext  *aContext,
+                          PRInt32          aXOffset,
+                          PRInt32          aYOffset,
+                          const nsIntRect &dragRect);
 
 };
 
diff --git a/widget/src/gtk2/nsNativeThemeGTK.cpp b/widget/src/gtk2/nsNativeThemeGTK.cpp
index 55e25cbd845e..e91f4840720f 100644
--- a/widget/src/gtk2/nsNativeThemeGTK.cpp
+++ b/widget/src/gtk2/nsNativeThemeGTK.cpp
@@ -814,7 +814,7 @@ nsNativeThemeGTK::DrawWidgetBackground(nsIRenderingContext* aContext,
 
 NS_IMETHODIMP
 nsNativeThemeGTK::GetWidgetBorder(nsIDeviceContext* aContext, nsIFrame* aFrame,
-                                  PRUint8 aWidgetType, nsMargin* aResult)
+                                  PRUint8 aWidgetType, nsIntMargin* aResult)
 {
   GtkTextDirection direction = GetTextDirection(aFrame);
   aResult->top = aResult->left = aResult->right = aResult->bottom = 0;
@@ -867,7 +867,7 @@ nsNativeThemeGTK::GetWidgetBorder(nsIDeviceContext* aContext, nsIFrame* aFrame,
 PRBool
 nsNativeThemeGTK::GetWidgetPadding(nsIDeviceContext* aContext,
                                    nsIFrame* aFrame, PRUint8 aWidgetType,
-                                   nsMargin* aResult)
+                                   nsIntMargin* aResult)
 {
   switch (aWidgetType) {
     case NS_THEME_BUTTON_FOCUS:
@@ -931,7 +931,7 @@ nsNativeThemeGTK::GetWidgetOverflow(nsIDeviceContext* aContext,
 NS_IMETHODIMP
 nsNativeThemeGTK::GetMinimumWidgetSize(nsIRenderingContext* aContext,
                                        nsIFrame* aFrame, PRUint8 aWidgetType,
-                                       nsSize* aResult, PRBool* aIsOverridable)
+                                       nsIntSize* aResult, PRBool* aIsOverridable)
 {
   aResult->width = aResult->height = 0;
   *aIsOverridable = PR_TRUE;
@@ -1087,7 +1087,7 @@ nsNativeThemeGTK::GetMinimumWidgetSize(nsIRenderingContext* aContext,
       nsCOMPtr<nsIDeviceContext> dc;
       aContext->GetDeviceContext(*getter_AddRefs(dc));
 
-      nsMargin border;
+      nsIntMargin border;
       nsNativeThemeGTK::GetWidgetBorder(dc, aFrame, aWidgetType, &border);
       aResult->width = border.left + border.right;
       aResult->height = border.top + border.bottom;
diff --git a/widget/src/gtk2/nsNativeThemeGTK.h b/widget/src/gtk2/nsNativeThemeGTK.h
index 291b0bc651da..b3f10100576e 100644
--- a/widget/src/gtk2/nsNativeThemeGTK.h
+++ b/widget/src/gtk2/nsNativeThemeGTK.h
@@ -60,12 +60,12 @@ public:
                                   const nsRect& aDirtyRect);
 
   NS_IMETHOD GetWidgetBorder(nsIDeviceContext* aContext, nsIFrame* aFrame,
-                             PRUint8 aWidgetType, nsMargin* aResult);
+                             PRUint8 aWidgetType, nsIntMargin* aResult);
 
   virtual NS_HIDDEN_(PRBool) GetWidgetPadding(nsIDeviceContext* aContext,
                                               nsIFrame* aFrame,
                                               PRUint8 aWidgetType,
-                                              nsMargin* aResult);
+                                              nsIntMargin* aResult);
 
   virtual NS_HIDDEN_(PRBool) GetWidgetOverflow(nsIDeviceContext* aContext,
                                                nsIFrame* aFrame,
@@ -74,7 +74,7 @@ public:
 
   NS_IMETHOD GetMinimumWidgetSize(nsIRenderingContext* aContext,
                                   nsIFrame* aFrame, PRUint8 aWidgetType,
-                                  nsSize* aResult, PRBool* aIsOverridable);
+                                  nsIntSize* aResult, PRBool* aIsOverridable);
 
   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, PRUint8 aWidgetType, 
                                 nsIAtom* aAttribute, PRBool* aShouldRepaint);
diff --git a/widget/src/gtk2/nsPrintSettingsGTK.cpp b/widget/src/gtk2/nsPrintSettingsGTK.cpp
index 53832fbadaae..2df0eb25d1eb 100644
--- a/widget/src/gtk2/nsPrintSettingsGTK.cpp
+++ b/widget/src/gtk2/nsPrintSettingsGTK.cpp
@@ -611,7 +611,7 @@ nsPrintSettingsGTK::InitUnwriteableMargin()
  * are ignored by the nsPrintSettings::SetUnwriteableMargin functions.)
  */
 NS_IMETHODIMP 
-nsPrintSettingsGTK::SetUnwriteableMarginInTwips(nsMargin& aUnwriteableMargin)
+nsPrintSettingsGTK::SetUnwriteableMarginInTwips(nsIntMargin& aUnwriteableMargin)
 {
   nsPrintSettings::SetUnwriteableMarginInTwips(aUnwriteableMargin);
   gtk_page_setup_set_top_margin(mPageSetup,
diff --git a/widget/src/gtk2/nsPrintSettingsGTK.h b/widget/src/gtk2/nsPrintSettingsGTK.h
index c0c85190f309..b340048668d2 100644
--- a/widget/src/gtk2/nsPrintSettingsGTK.h
+++ b/widget/src/gtk2/nsPrintSettingsGTK.h
@@ -121,7 +121,7 @@ public:
   NS_IMETHOD GetPaperName(PRUnichar * *aPaperName);
   NS_IMETHOD SetPaperName(const PRUnichar * aPaperName);
 
-  NS_IMETHOD SetUnwriteableMarginInTwips(nsMargin& aUnwriteableMargin);
+  NS_IMETHOD SetUnwriteableMarginInTwips(nsIntMargin& aUnwriteableMargin);
   NS_IMETHOD SetUnwriteableMarginTop(double aUnwriteableMarginTop);
   NS_IMETHOD SetUnwriteableMarginLeft(double aUnwriteableMarginLeft);
   NS_IMETHOD SetUnwriteableMarginBottom(double aUnwriteableMarginBottom);
diff --git a/widget/src/gtk2/nsScreenGtk.cpp b/widget/src/gtk2/nsScreenGtk.cpp
index 0a927d5c978b..68c6e659f840 100644
--- a/widget/src/gtk2/nsScreenGtk.cpp
+++ b/widget/src/gtk2/nsScreenGtk.cpp
@@ -114,7 +114,7 @@ nsScreenGtk :: Init (GdkWindow *aRootWindow)
   // changes to this rect.  We could listen for "size_changed" signals
   // on the default screen to do this, except that doesn't work with
   // versions of GDK predating the GdkScreen object.  See bug 256646.
-  mAvailRect = mRect = nsRect(0, 0, gdk_screen_width(), gdk_screen_height());
+  mAvailRect = mRect = nsIntRect(0, 0, gdk_screen_width(), gdk_screen_height());
 
 #ifdef MOZ_X11
   // We need to account for the taskbar, etc in the available rect.
@@ -162,8 +162,8 @@ nsScreenGtk :: Init (GdkWindow *aRootWindow)
     int num_items = length_returned / sizeof(long);
 
     for (int i = 0; i < num_items; i += 4) {
-      nsRect workarea(workareas[i],     workareas[i + 1],
-                      workareas[i + 2], workareas[i + 3]);
+      nsIntRect workarea(workareas[i],     workareas[i + 1],
+                         workareas[i + 2], workareas[i + 3]);
       if (!mRect.Contains(workarea)) {
         // Note that we hit this when processing screen size changes,
         // since we'll get the configure event before the toolbars have
@@ -187,8 +187,8 @@ nsScreenGtk :: Init (GdkWindow *aRootWindow)
 void
 nsScreenGtk :: Init (XineramaScreenInfo *aScreenInfo)
 {
-  nsRect xineRect(aScreenInfo->x_org, aScreenInfo->y_org,
-                  aScreenInfo->width, aScreenInfo->height);
+  nsIntRect xineRect(aScreenInfo->x_org, aScreenInfo->y_org,
+                     aScreenInfo->width, aScreenInfo->height);
 
   mScreenNum = aScreenInfo->screen_number;
 
diff --git a/widget/src/gtk2/nsScreenGtk.h b/widget/src/gtk2/nsScreenGtk.h
index 825bfb0e9bf3..258e6a2c7d5b 100644
--- a/widget/src/gtk2/nsScreenGtk.h
+++ b/widget/src/gtk2/nsScreenGtk.h
@@ -72,8 +72,8 @@ public:
 
 private:
   PRUint32 mScreenNum;
-  nsRect mRect; // in pixels, not twips
-  nsRect mAvailRect; // in pixels, not twips
+  nsIntRect mRect;
+  nsIntRect mAvailRect;
 };
 
 #endif  // nsScreenGtk_h___ 
diff --git a/widget/src/gtk2/nsScreenManagerGtk.cpp b/widget/src/gtk2/nsScreenManagerGtk.cpp
index 488b168afaeb..612ee5c5006c 100644
--- a/widget/src/gtk2/nsScreenManagerGtk.cpp
+++ b/widget/src/gtk2/nsScreenManagerGtk.cpp
@@ -257,7 +257,7 @@ nsScreenManagerGtk :: Init()
 // Returns the screen that contains the rectangle. If the rect overlaps
 // multiple screens, it picks the screen with the greatest area of intersection.
 //
-// The coordinates are in pixels (not twips) and in screen coordinates.
+// The coordinates are in pixels (not app units) and in screen coordinates.
 //
 NS_IMETHODIMP
 nsScreenManagerGtk :: ScreenForRect ( PRInt32 aX, PRInt32 aY,
@@ -279,13 +279,13 @@ nsScreenManagerGtk :: ScreenForRect ( PRInt32 aX, PRInt32 aY,
     // walk the list of screens and find the one that has the most
     // surface area.
     PRUint32 area = 0;
-    nsRect   windowRect(aX, aY, aWidth, aHeight);
+    nsIntRect windowRect(aX, aY, aWidth, aHeight);
     for (PRInt32 i = 0, i_end = mCachedScreenArray.Count(); i < i_end; ++i) {
       PRInt32  x, y, width, height;
       x = y = width = height = 0;
       mCachedScreenArray[i]->GetRect(&x, &y, &width, &height);
       // calculate the surface area
-      nsRect screenRect(x, y, width, height);
+      nsIntRect screenRect(x, y, width, height);
       screenRect.IntersectRect(screenRect, windowRect);
       PRUint32 tempArea = screenRect.width * screenRect.height;
       if (tempArea >= area) {
diff --git a/widget/src/gtk2/nsWindow.cpp b/widget/src/gtk2/nsWindow.cpp
index 57ba33c2280c..24266f55b210 100644
--- a/widget/src/gtk2/nsWindow.cpp
+++ b/widget/src/gtk2/nsWindow.cpp
@@ -465,7 +465,7 @@ NS_IMPL_ISUPPORTS_INHERITED1(nsWindow, nsCommonWidget,
 
 NS_IMETHODIMP
 nsWindow::Create(nsIWidget        *aParent,
-                 const nsRect     &aRect,
+                 const nsIntRect  &aRect,
                  EVENT_CALLBACK   aHandleEventFunction,
                  nsIDeviceContext *aContext,
                  nsIAppShell      *aAppShell,
@@ -479,7 +479,7 @@ nsWindow::Create(nsIWidget        *aParent,
 
 NS_IMETHODIMP
 nsWindow::Create(nsNativeWidget aParent,
-                 const nsRect     &aRect,
+                 const nsIntRect  &aRect,
                  EVENT_CALLBACK   aHandleEventFunction,
                  nsIDeviceContext *aContext,
                  nsIAppShell      *aAppShell,
@@ -994,9 +994,9 @@ nsWindow::SetFocus(PRBool aRaise)
 }
 
 NS_IMETHODIMP
-nsWindow::GetScreenBounds(nsRect &aRect)
+nsWindow::GetScreenBounds(nsIntRect &aRect)
 {
-    nsRect origin(0, 0, mBounds.width, mBounds.height);
+    nsIntRect origin(0, 0, mBounds.width, mBounds.height);
     WidgetToScreen(origin, aRect);
     LOG(("GetScreenBounds %d %d | %d %d | %d %d\n",
          aRect.x, aRect.y,
@@ -1264,8 +1264,8 @@ nsWindow::Invalidate(PRBool aIsSynchronous)
 }
 
 NS_IMETHODIMP
-nsWindow::Invalidate(const nsRect &aRect,
-                     PRBool        aIsSynchronous)
+nsWindow::Invalidate(const nsIntRect &aRect,
+                     PRBool           aIsSynchronous)
 {
     GdkRectangle rect;
 
@@ -1331,9 +1331,9 @@ nsWindow::SetColorMap(nsColorMap *aColorMap)
 }
 
 NS_IMETHODIMP
-nsWindow::Scroll(PRInt32  aDx,
-                 PRInt32  aDy,
-                 nsRect  *aClipRect)
+nsWindow::Scroll(PRInt32     aDx,
+                 PRInt32     aDy,
+                 nsIntRect  *aClipRect)
 {
     if (!mDrawingarea)
         return NS_OK;
@@ -1349,7 +1349,7 @@ nsWindow::Scroll(PRInt32  aDx,
 
     // Update bounds on our child windows
     for (nsIWidget* kid = mFirstChild; kid; kid = kid->GetNextSibling()) {
-        nsRect bounds;
+        nsIntRect bounds;
         kid->GetBounds(bounds);
         bounds.x += aDx;
         bounds.y += aDy;
@@ -1373,9 +1373,9 @@ nsWindow::ScrollWidgets(PRInt32 aDx,
 }
 
 NS_IMETHODIMP
-nsWindow::ScrollRect(nsRect  &aSrcRect,
-                     PRInt32  aDx,
-                     PRInt32  aDy)
+nsWindow::ScrollRect(nsIntRect  &aSrcRect,
+                     PRInt32     aDx,
+                     PRInt32     aDy)
 {
     return NS_ERROR_NOT_IMPLEMENTED;
 }
@@ -1500,7 +1500,7 @@ nsWindow::ShowMenuBar(PRBool aShow)
 }
 
 NS_IMETHODIMP
-nsWindow::WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect)
+nsWindow::WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect)
 {
     gint x = 0, y = 0;
 
@@ -1523,7 +1523,7 @@ nsWindow::WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect)
 }
 
 NS_IMETHODIMP
-nsWindow::ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect)
+nsWindow::ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect)
 {
     gint x = 0, y = 0;
 
@@ -1895,7 +1895,7 @@ nsWindow::OnExposeEvent(GtkWidget *aWidget, GdkEventExpose *aEvent)
 
         if (bufferPixmap) {
             bufferPixmapSurface = GetSurfaceForGdkDrawable(GDK_DRAWABLE(bufferPixmap),
-                                                           nsSize(bufferPixmapSize.width, bufferPixmapSize.height));
+                                                           nsIntSize(bufferPixmapSize.width, bufferPixmapSize.height));
 
             if (bufferPixmapSurface && bufferPixmapSurface->CairoStatus()) {
                 bufferPixmapSurface = nsnull;
@@ -1969,8 +1969,8 @@ nsWindow::OnExposeEvent(GtkWidget *aWidget, GdkEventExpose *aEvent)
                         imgCtx->Paint();
                     }
 
-                    UpdateTranslucentWindowAlphaInternal(nsRect(boundsRect.x, boundsRect.y,
-                                                                boundsRect.width, boundsRect.height),
+                    UpdateTranslucentWindowAlphaInternal(nsIntRect(boundsRect.x, boundsRect.y,
+                                                                   boundsRect.width, boundsRect.height),
                                                          img->Data(), img->Stride());
                 }
             } else {
@@ -2021,7 +2021,7 @@ nsWindow::OnConfigureEvent(GtkWidget *aWidget, GdkEventConfigure *aEvent)
     if (mIsTopLevel) {
         mPlaced = PR_TRUE;
         // Need to translate this into the right coordinates
-        nsRect oldrect, newrect;
+        nsIntRect oldrect, newrect;
         WidgetToScreen(oldrect, newrect);
         mBounds.x = newrect.x;
         mBounds.y = newrect.y;
@@ -2047,8 +2047,8 @@ nsWindow::OnSizeAllocate(GtkWidget *aWidget, GtkAllocation *aAllocation)
          (void *)this, aAllocation->x, aAllocation->y,
          aAllocation->width, aAllocation->height));
 
-    nsRect rect(aAllocation->x, aAllocation->y,
-                aAllocation->width, aAllocation->height);
+    nsIntRect rect(aAllocation->x, aAllocation->y,
+                   aAllocation->width, aAllocation->height);
 
     ResizeTransparencyBitmap(rect.width, rect.height);
 
@@ -2256,8 +2256,8 @@ nsWindow::OnMotionNotifyEvent(GtkWidget *aWidget, GdkEventMotion *aEvent)
             event.refPoint.x = nscoord(aEvent->x);
             event.refPoint.y = nscoord(aEvent->y);
         } else {
-            nsRect windowRect;
-            ScreenToWidget(nsRect(nscoord(aEvent->x_root), nscoord(aEvent->y_root), 1, 1), windowRect);
+            nsIntRect windowRect;
+            ScreenToWidget(nsIntRect(NSToIntFloor(aEvent->x_root), NSToIntFloor(aEvent->y_root), 1, 1), windowRect);
 
             event.refPoint.x = windowRect.x;
             event.refPoint.y = windowRect.y;
@@ -2287,8 +2287,8 @@ nsWindow::InitButtonEvent(nsMouseEvent &aEvent,
         aEvent.refPoint.x = nscoord(aGdkEvent->x);
         aEvent.refPoint.y = nscoord(aGdkEvent->y);
     } else {
-        nsRect windowRect;
-        ScreenToWidget(nsRect(nscoord(aGdkEvent->x_root), nscoord(aGdkEvent->y_root), 1, 1), windowRect);
+        nsIntRect windowRect;
+        ScreenToWidget(nsIntRect(NSToIntFloor(aGdkEvent->x_root), NSToIntFloor(aGdkEvent->y_root), 1, 1), windowRect);
 
         aEvent.refPoint.x = windowRect.x;
         aEvent.refPoint.y = windowRect.y;
@@ -2838,8 +2838,8 @@ nsWindow::OnScrollEvent(GtkWidget *aWidget, GdkEventScroll *aEvent)
         // XXX we're never quite sure which GdkWindow the event came from due to our custom bubbling
         // in scroll_event_cb(), so use ScreenToWidget to translate the screen root coordinates into
         // coordinates relative to this widget.
-        nsRect windowRect;
-        ScreenToWidget(nsRect(nscoord(aEvent->x_root), nscoord(aEvent->y_root), 1, 1), windowRect);
+        nsIntRect windowRect;
+        ScreenToWidget(nsIntRect(NSToIntFloor(aEvent->x_root), NSToIntFloor(aEvent->y_root), 1, 1), windowRect);
 
         event.refPoint.x = windowRect.x;
         event.refPoint.y = windowRect.y;
@@ -3276,7 +3276,7 @@ GetBrandName(nsXPIDLString& brandName)
 nsresult
 nsWindow::NativeCreate(nsIWidget        *aParent,
                        nsNativeWidget    aNativeParent,
-                       const nsRect     &aRect,
+                       const nsIntRect  &aRect,
                        EVENT_CALLBACK    aHandleEventFunction,
                        nsIDeviceContext *aContext,
                        nsIAppShell      *aAppShell,
@@ -3897,10 +3897,10 @@ nsWindow::NativeShow (PRBool  aAction)
     }
 }
 
-nsSize
-nsWindow::GetSafeWindowSize(nsSize aSize)
+nsIntSize
+nsWindow::GetSafeWindowSize(const nsIntSize &aSize)
 {
-    nsSize result = aSize;
+    nsIntSize result = aSize;
     const PRInt32 kInt16Max = 32767;
     if (result.width > kInt16Max) {
         NS_WARNING("Clamping huge window width");
@@ -4026,7 +4026,7 @@ nsWindow::ResizeTransparencyBitmap(PRInt32 aNewWidth, PRInt32 aNewHeight)
 
 static PRBool
 ChangedMaskBits(gchar* aMaskBits, PRInt32 aMaskWidth, PRInt32 aMaskHeight,
-        const nsRect& aRect, PRUint8* aAlphas, PRInt32 aStride)
+        const nsIntRect& aRect, PRUint8* aAlphas, PRInt32 aStride)
 {
     PRInt32 x, y, xMax = aRect.XMost(), yMax = aRect.YMost();
     PRInt32 maskBytesPerRow = (aMaskWidth + 7)/8;
@@ -4052,7 +4052,7 @@ ChangedMaskBits(gchar* aMaskBits, PRInt32 aMaskWidth, PRInt32 aMaskHeight,
 
 static
 void UpdateMaskBits(gchar* aMaskBits, PRInt32 aMaskWidth, PRInt32 aMaskHeight,
-        const nsRect& aRect, PRUint8* aAlphas, PRInt32 aStride)
+        const nsIntRect& aRect, PRUint8* aAlphas, PRInt32 aStride)
 {
     PRInt32 x, y, xMax = aRect.XMost(), yMax = aRect.YMost();
     PRInt32 maskBytesPerRow = (aMaskWidth + 7)/8;
@@ -4087,7 +4087,7 @@ nsWindow::ApplyTransparencyBitmap()
 }
 
 nsresult
-nsWindow::UpdateTranslucentWindowAlphaInternal(const nsRect& aRect,
+nsWindow::UpdateTranslucentWindowAlphaInternal(const nsIntRect& aRect,
                                                PRUint8* aAlphas, PRInt32 aStride)
 {
     if (!mShell) {
@@ -5507,7 +5507,7 @@ void
 key_event_to_context_menu_event(nsMouseEvent &aEvent,
                                 GdkEventKey *aGdkEvent)
 {
-    aEvent.refPoint = nsPoint(0, 0);
+    aEvent.refPoint = nsIntPoint(0, 0);
     aEvent.isShift = PR_FALSE;
     aEvent.isControl = PR_FALSE;
     aEvent.isAlt = PR_FALSE;
@@ -6576,7 +6576,7 @@ IM_get_input_context(nsWindow *aWindow)
 #ifdef MOZ_X11
 /* static */ already_AddRefed<gfxASurface>
 nsWindow::GetSurfaceForGdkDrawable(GdkDrawable* aDrawable,
-                                   const nsSize& aSize)
+                                   const nsIntSize& aSize)
 {
     GdkVisual* visual = gdk_drawable_get_visual(aDrawable);
     Display* xDisplay = gdk_x11_drawable_get_xdisplay(aDrawable);
diff --git a/widget/src/gtk2/nsWindow.h b/widget/src/gtk2/nsWindow.h
index 32773fc390ed..12363cf483b4 100644
--- a/widget/src/gtk2/nsWindow.h
+++ b/widget/src/gtk2/nsWindow.h
@@ -87,14 +87,14 @@ public:
 
     // nsIWidget
     NS_IMETHOD         Create(nsIWidget        *aParent,
-                              const nsRect     &aRect,
+                              const nsIntRect  &aRect,
                               EVENT_CALLBACK   aHandleEventFunction,
                               nsIDeviceContext *aContext,
                               nsIAppShell      *aAppShell,
                               nsIToolkit       *aToolkit,
                               nsWidgetInitData *aInitData);
     NS_IMETHOD         Create(nsNativeWidget aParent,
-                              const nsRect     &aRect,
+                              const nsIntRect  &aRect,
                               EVENT_CALLBACK   aHandleEventFunction,
                               nsIDeviceContext *aContext,
                               nsIAppShell      *aAppShell,
@@ -116,7 +116,7 @@ public:
     NS_IMETHOD         SetSizeMode(PRInt32 aMode);
     NS_IMETHOD         Enable(PRBool aState);
     NS_IMETHOD         SetFocus(PRBool aRaise = PR_FALSE);
-    NS_IMETHOD         GetScreenBounds(nsRect &aRect);
+    NS_IMETHOD         GetScreenBounds(nsIntRect &aRect);
     NS_IMETHOD         SetForegroundColor(const nscolor &aColor);
     NS_IMETHOD         SetBackgroundColor(const nscolor &aColor);
     NS_IMETHOD         SetCursor(nsCursor aCursor);
@@ -124,20 +124,20 @@ public:
                                  PRUint32 aHotspotX, PRUint32 aHotspotY);
     NS_IMETHOD         Validate();
     NS_IMETHOD         Invalidate(PRBool aIsSynchronous);
-    NS_IMETHOD         Invalidate(const nsRect &aRect,
-                                  PRBool        aIsSynchronous);
+    NS_IMETHOD         Invalidate(const nsIntRect &aRect,
+                                  PRBool           aIsSynchronous);
     NS_IMETHOD         InvalidateRegion(const nsIRegion *aRegion,
                                         PRBool           aIsSynchronous);
     NS_IMETHOD         Update();
     NS_IMETHOD         SetColorMap(nsColorMap *aColorMap);
-    NS_IMETHOD         Scroll(PRInt32  aDx,
-                              PRInt32  aDy,
-                              nsRect  *aClipRect);
+    NS_IMETHOD         Scroll(PRInt32     aDx,
+                              PRInt32     aDy,
+                              nsIntRect  *aClipRect);
     NS_IMETHOD         ScrollWidgets(PRInt32 aDx,
                                      PRInt32 aDy);
-    NS_IMETHOD         ScrollRect(nsRect  &aSrcRect,
-                                  PRInt32  aDx,
-                                  PRInt32  aDy);
+    NS_IMETHOD         ScrollRect(nsIntRect  &aSrcRect,
+                                  PRInt32     aDx,
+                                  PRInt32     aDy);
     virtual void*      GetNativeData(PRUint32 aDataType);
     NS_IMETHOD         SetBorderStyle(nsBorderStyle aBorderStyle);
     NS_IMETHOD         SetTitle(const nsAString& aTitle);
@@ -145,10 +145,10 @@ public:
     NS_IMETHOD         SetWindowClass(const nsAString& xulWinType);
     NS_IMETHOD         SetMenuBar(void * aMenuBar);
     NS_IMETHOD         ShowMenuBar(PRBool aShow);
-    NS_IMETHOD         WidgetToScreen(const nsRect& aOldRect,
-                                      nsRect& aNewRect);
-    NS_IMETHOD         ScreenToWidget(const nsRect& aOldRect,
-                                      nsRect& aNewRect);
+    NS_IMETHOD         WidgetToScreen(const nsIntRect& aOldRect,
+                                      nsIntRect& aNewRect);
+    NS_IMETHOD         ScreenToWidget(const nsIntRect& aOldRect,
+                                      nsIntRect& aNewRect);
     NS_IMETHOD         BeginResizingChildren(void);
     NS_IMETHOD         EndResizingChildren(void);
     NS_IMETHOD         EnableDragDrop(PRBool aEnable);
@@ -230,7 +230,7 @@ public:
 
     nsresult           NativeCreate(nsIWidget        *aParent,
                                     nsNativeWidget    aNativeParent,
-                                    const nsRect     &aRect,
+                                    const nsIntRect   &aRect,
                                     EVENT_CALLBACK    aHandleEventFunction,
                                     nsIDeviceContext *aContext,
                                     nsIAppShell      *aAppShell,
@@ -248,7 +248,7 @@ public:
                                     PRBool  aRepaint);
 
     void               NativeShow  (PRBool  aAction);
-    virtual nsSize     GetSafeWindowSize(nsSize aSize);
+    virtual nsIntSize  GetSafeWindowSize(const nsIntSize &aSize);
 
     void               EnsureGrabs  (void);
     void               GrabPointer  (void);
@@ -368,13 +368,13 @@ public:
    void                ApplyTransparencyBitmap();
    virtual void        SetTransparencyMode(nsTransparencyMode aMode);
    virtual nsTransparencyMode GetTransparencyMode();
-   nsresult            UpdateTranslucentWindowAlphaInternal(const nsRect& aRect,
+   nsresult            UpdateTranslucentWindowAlphaInternal(const nsIntRect& aRect,
                                                             PRUint8* aAlphas, PRInt32 aStride);
 
     gfxASurface       *GetThebesSurface();
 
     static already_AddRefed<gfxASurface> GetSurfaceForGdkDrawable(GdkDrawable* aDrawable,
-                                                                  const nsSize& aSize);
+                                                                  const nsIntSize& aSize);
 
 #ifdef ACCESSIBILITY
     static PRBool      sAccessibilityEnabled;
diff --git a/widget/src/windows/nsDragService.cpp b/widget/src/windows/nsDragService.cpp
index 4c589b6a5b98..37c0164d552b 100644
--- a/widget/src/windows/nsDragService.cpp
+++ b/widget/src/windows/nsDragService.cpp
@@ -109,7 +109,7 @@ nsDragService::CreateDragImage(nsIDOMNode *aDOMNode,
     return PR_FALSE;
 
   // Prepare the drag image
-  nsRect dragRect;
+  nsIntRect dragRect;
   nsRefPtr<gfxASurface> surface;
   nsPresContext* pc;
   DrawDrag(aDOMNode, aRegion,
diff --git a/widget/src/windows/nsNativeThemeWin.cpp b/widget/src/windows/nsNativeThemeWin.cpp
index d5ef57febaca..09cade67ced4 100644
--- a/widget/src/windows/nsNativeThemeWin.cpp
+++ b/widget/src/windows/nsNativeThemeWin.cpp
@@ -98,7 +98,7 @@ nsNativeThemeWin::~nsNativeThemeWin() {
   nsUXThemeData::Invalidate();
 }
 
-static void GetNativeRect(const nsRect& aSrc, RECT& aDst) 
+static void GetNativeRect(const nsIntRect& aSrc, RECT& aDst) 
 {
   aDst.top = aSrc.y;
   aDst.bottom = aSrc.y + aSrc.height;
@@ -1186,7 +1186,7 @@ NS_IMETHODIMP
 nsNativeThemeWin::GetWidgetBorder(nsIDeviceContext* aContext, 
                                   nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsMargin* aResult)
+                                  nsIntMargin* aResult)
 {
   HANDLE theme = GetTheme(aWidgetType);
   if (!theme)
@@ -1235,7 +1235,7 @@ nsNativeThemeWin::GetWidgetBorder(nsIDeviceContext* aContext,
     return NS_ERROR_FAILURE;
 
   // Now compute the delta in each direction and place it in our
-  // nsMargin struct.
+  // nsIntMargin struct.
   aResult->top = contentRect.top - outerRect.top;
   aResult->bottom = outerRect.bottom - contentRect.bottom;
   aResult->left = contentRect.left - outerRect.left;
@@ -1268,7 +1268,7 @@ PRBool
 nsNativeThemeWin::GetWidgetPadding(nsIDeviceContext* aContext, 
                                    nsIFrame* aFrame,
                                    PRUint8 aWidgetType,
-                                   nsMargin* aResult)
+                                   nsIntMargin* aResult)
 {
   switch (aWidgetType) {
     // Radios and checkboxes return a fixed size in GetMinimumWidgetSize
@@ -1414,7 +1414,7 @@ nsNativeThemeWin::GetWidgetOverflow(nsIDeviceContext* aContext,
 NS_IMETHODIMP
 nsNativeThemeWin::GetMinimumWidgetSize(nsIRenderingContext* aContext, nsIFrame* aFrame,
                                        PRUint8 aWidgetType,
-                                       nsSize* aResult, PRBool* aIsOverridable)
+                                       nsIntSize* aResult, PRBool* aIsOverridable)
 {
   (*aResult).width = (*aResult).height = 0;
   *aIsOverridable = PR_TRUE;
@@ -1743,7 +1743,7 @@ nsresult
 nsNativeThemeWin::ClassicGetWidgetBorder(nsIDeviceContext* aContext, 
                                   nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsMargin* aResult)
+                                  nsIntMargin* aResult)
 {
   switch (aWidgetType) {
     case NS_THEME_BUTTON:
@@ -1822,7 +1822,7 @@ nsNativeThemeWin::ClassicGetWidgetBorder(nsIDeviceContext* aContext,
 nsresult
 nsNativeThemeWin::ClassicGetMinimumWidgetSize(nsIRenderingContext* aContext, nsIFrame* aFrame,
                                        PRUint8 aWidgetType,
-                                       nsSize* aResult, PRBool* aIsOverridable)
+                                       nsIntSize* aResult, PRBool* aIsOverridable)
 {
   (*aResult).width = (*aResult).height = 0;
   *aIsOverridable = PR_TRUE;
diff --git a/widget/src/windows/nsNativeThemeWin.h b/widget/src/windows/nsNativeThemeWin.h
index b0e7993af3ba..172e8bbd896d 100644
--- a/widget/src/windows/nsNativeThemeWin.h
+++ b/widget/src/windows/nsNativeThemeWin.h
@@ -43,6 +43,9 @@
 #include "nsNativeTheme.h"
 #include <windows.h>
 
+struct nsIntRect;
+struct nsIntSize;
+
 class nsNativeThemeWin : private nsNativeTheme,
                          public nsITheme {
 public:
@@ -58,12 +61,12 @@ public:
   NS_IMETHOD GetWidgetBorder(nsIDeviceContext* aContext, 
                              nsIFrame* aFrame,
                              PRUint8 aWidgetType,
-                             nsMargin* aResult);
+                             nsIntMargin* aResult);
 
   virtual PRBool GetWidgetPadding(nsIDeviceContext* aContext,
                                   nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsMargin* aResult);
+                                  nsIntMargin* aResult);
 
   virtual PRBool GetWidgetOverflow(nsIDeviceContext* aContext,
                                    nsIFrame* aFrame,
@@ -72,7 +75,7 @@ public:
 
   NS_IMETHOD GetMinimumWidgetSize(nsIRenderingContext* aContext, nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsSize* aResult,
+                                  nsIntSize* aResult,
                                   PRBool* aIsOverridable);
 
   NS_IMETHOD WidgetStateChanged(nsIFrame* aFrame, PRUint8 aWidgetType, 
@@ -107,11 +110,11 @@ protected:
   nsresult ClassicGetWidgetBorder(nsIDeviceContext* aContext, 
                              nsIFrame* aFrame,
                              PRUint8 aWidgetType,
-                             nsMargin* aResult);
+                             nsIntMargin* aResult);
 
   nsresult ClassicGetMinimumWidgetSize(nsIRenderingContext* aContext, nsIFrame* aFrame,
                                   PRUint8 aWidgetType,
-                                  nsSize* aResult,
+                                  nsIntSize* aResult,
                                   PRBool* aIsOverridable);
 
   PRBool ClassicThemeSupportsWidget(nsPresContext* aPresContext, 
diff --git a/widget/src/windows/nsWindow.cpp b/widget/src/windows/nsWindow.cpp
index 41c867a9eca6..c9219b4aec09 100644
--- a/widget/src/windows/nsWindow.cpp
+++ b/widget/src/windows/nsWindow.cpp
@@ -820,7 +820,7 @@ NS_METHOD nsWindow::EndResizingChildren(void)
   return NS_OK;
 }
 
-NS_METHOD nsWindow::WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect)
+NS_METHOD nsWindow::WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect)
 {
   POINT point;
   point.x = aOldRect.x;
@@ -833,7 +833,7 @@ NS_METHOD nsWindow::WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect)
   return NS_OK;
 }
 
-NS_METHOD nsWindow::ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect)
+NS_METHOD nsWindow::ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect)
 {
   POINT point;
   point.x = aOldRect.x;
@@ -869,10 +869,10 @@ LPARAM nsWindow::lParamToClient(LPARAM lParam)
 // Initialize an event to dispatch
 //
 //-------------------------------------------------------------------------
-void nsWindow::InitEvent(nsGUIEvent& event, nsPoint* aPoint)
+void nsWindow::InitEvent(nsGUIEvent& event, nsIntPoint* aPoint)
 {
   if (nsnull == aPoint) {     // use the point from the event
-    // get the message position in client coordinates and in twips
+    // get the message position in client coordinates
     if (mWnd != NULL) {
 
       DWORD pos = ::GetMessagePos();
@@ -1199,7 +1199,7 @@ LRESULT CALLBACK nsWindow::DefaultWindowProc(HWND hWnd, UINT msg, WPARAM wParam,
 
 nsresult
 nsWindow::StandardWindowCreate(nsIWidget *aParent,
-                               const nsRect &aRect,
+                               const nsIntRect &aRect,
                                EVENT_CALLBACK aHandleEventFunction,
                                nsIDeviceContext *aContext,
                                nsIAppShell *aAppShell,
@@ -1363,7 +1363,7 @@ nsWindow::StandardWindowCreate(nsIWidget *aParent,
 //
 //-------------------------------------------------------------------------
 NS_METHOD nsWindow::Create(nsIWidget *aParent,
-                           const nsRect &aRect,
+                           const nsIntRect &aRect,
                            EVENT_CALLBACK aHandleEventFunction,
                            nsIDeviceContext *aContext,
                            nsIAppShell *aAppShell,
@@ -1385,7 +1385,7 @@ NS_METHOD nsWindow::Create(nsIWidget *aParent,
 //-------------------------------------------------------------------------
 
 NS_METHOD nsWindow::Create(nsNativeWidget aParent,
-                           const nsRect &aRect,
+                           const nsIntRect &aRect,
                            EVENT_CALLBACK aHandleEventFunction,
                            nsIDeviceContext *aContext,
                            nsIAppShell *aAppShell,
@@ -2131,7 +2131,7 @@ NS_METHOD nsWindow::SetFocus(PRBool aRaise)
 // Get this component dimension
 //
 //-------------------------------------------------------------------------
-NS_METHOD nsWindow::GetBounds(nsRect &aRect)
+NS_METHOD nsWindow::GetBounds(nsIntRect &aRect)
 {
   if (mWnd) {
     RECT r;
@@ -2163,7 +2163,7 @@ NS_METHOD nsWindow::GetBounds(nsRect &aRect)
 // Get this component dimension
 //
 //-------------------------------------------------------------------------
-NS_METHOD nsWindow::GetClientBounds(nsRect &aRect)
+NS_METHOD nsWindow::GetClientBounds(nsIntRect &aRect)
 {
   if (mWnd) {
     RECT r;
@@ -2183,7 +2183,7 @@ NS_METHOD nsWindow::GetClientBounds(nsRect &aRect)
 
 //get the bounds, but don't take into account the client size
 
-void nsWindow::GetNonClientBounds(nsRect &aRect)
+void nsWindow::GetNonClientBounds(nsIntRect &aRect)
 {
   if (mWnd) {
     RECT r;
@@ -2209,7 +2209,7 @@ void nsWindow::GetNonClientBounds(nsRect &aRect)
 }
 
 // like GetBounds, but don't offset by the parent
-NS_METHOD nsWindow::GetScreenBounds(nsRect &aRect)
+NS_METHOD nsWindow::GetScreenBounds(nsIntRect &aRect)
 {
   if (mWnd) {
     RECT r;
@@ -2682,7 +2682,7 @@ NS_METHOD nsWindow::Invalidate(PRBool aIsSynchronous)
 // Invalidate this component visible area
 //
 //-------------------------------------------------------------------------
-NS_METHOD nsWindow::Invalidate(const nsRect & aRect, PRBool aIsSynchronous)
+NS_METHOD nsWindow::Invalidate(const nsIntRect & aRect, PRBool aIsSynchronous)
 {
   if (mWnd)
   {
@@ -2860,7 +2860,7 @@ BOOL CALLBACK nsWindow::InvalidateForeignChildWindows(HWND aWnd, LPARAM aMsg)
 //
 //-------------------------------------------------------------------------
 //XXX Scroll is obsolete and should go away soon
-NS_METHOD nsWindow::Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *aClipRect)
+NS_METHOD nsWindow::Scroll(PRInt32 aDx, PRInt32 aDy, nsIntRect *aClipRect)
 {
   RECT  trect;
 
@@ -2891,7 +2891,7 @@ NS_IMETHODIMP nsWindow::ScrollWidgets(PRInt32 aDx, PRInt32 aDy)
   return NS_OK;
 }
 
-NS_IMETHODIMP nsWindow::ScrollRect(nsRect &aRect, PRInt32 aDx, PRInt32 aDy)
+NS_IMETHODIMP nsWindow::ScrollRect(nsIntRect &aRect, PRInt32 aDx, PRInt32 aDy)
 {
   RECT  trect;
 
@@ -2923,7 +2923,7 @@ BOOL nsWindow::CallMethod(MethodInfo *info)
     case nsWindow::CREATE:
       NS_ASSERTION(info->nArgs == 7, "Wrong number of arguments to CallMethod");
       Create((nsIWidget*)(info->args[0]),
-             (nsRect&)*(nsRect*)(info->args[1]),
+             (nsIntRect&)*(nsIntRect*)(info->args[1]),
              (EVENT_CALLBACK)(info->args[2]),
              (nsIDeviceContext*)(info->args[3]),
              (nsIAppShell *)(info->args[4]),
@@ -2934,7 +2934,7 @@ BOOL nsWindow::CallMethod(MethodInfo *info)
     case nsWindow::CREATE_NATIVE:
       NS_ASSERTION(info->nArgs == 7, "Wrong number of arguments to CallMethod");
       Create((nsNativeWidget)(info->args[0]),
-             (nsRect&)*(nsRect*)(info->args[1]),
+             (nsIntRect&)*(nsIntRect*)(info->args[1]),
              (EVENT_CALLBACK)(info->args[2]),
              (nsIDeviceContext*)(info->args[3]),
              (nsIAppShell *)(info->args[4]),
@@ -3021,7 +3021,7 @@ PRBool nsWindow::DispatchKeyEvent(PRUint32 aEventType, WORD aCharCode,
                    UINT aVirtualCharCode, LPARAM aKeyData, PRUint32 aFlags)
 {
   nsKeyEvent event(PR_TRUE, aEventType, this);
-  nsPoint point(0, 0);
+  nsIntPoint point(0, 0);
 
   InitEvent(event, &point); // this add ref's event.widget
 
@@ -4134,7 +4134,7 @@ PRBool nsWindow::ProcessMessage(UINT msg, WPARAM wParam, LPARAM lParam, LRESULT
       WORD wNotifyCode = HIWORD(wParam); // notification code
       if ((CBN_SELENDOK == wNotifyCode) || (CBN_SELENDCANCEL == wNotifyCode)) { // Combo box change
         nsGUIEvent event(PR_TRUE, NS_CONTROL_CHANGE, this);
-        nsPoint point(0,0);
+        nsIntPoint point(0,0);
         InitEvent(event, &point); // this add ref's event.widget
         result = DispatchWindowEvent(&event);
       } else if (wNotifyCode == 0) { // Menu selection
@@ -4855,7 +4855,7 @@ PRBool nsWindow::ProcessMessage(UINT msg, WPARAM wParam, LPARAM lParam, LRESULT
         PRInt32 newWidth, newHeight;
         newWidth = PRInt32(r.right - r.left);
         newHeight = PRInt32(r.bottom - r.top);
-        nsRect rect(wp->x, wp->y, newWidth, newHeight);
+        nsIntRect rect(wp->x, wp->y, newWidth, newHeight);
 
 
 #ifdef MOZ_XUL
@@ -5764,7 +5764,6 @@ ConvertHRGNToRegion(HRGN aRgn)
 //-------------------------------------------------------------------------
 PRBool nsWindow::OnPaint(HDC aDC)
 {
-  nsRect bounds;
   PRBool result = PR_TRUE;
   PAINTSTRUCT ps;
   nsEventStatus eventStatus = nsEventStatus_eIgnore;
@@ -5948,7 +5947,7 @@ PRBool nsWindow::OnPaint(HDC aDC)
 // Send a resize message to the listener
 //
 //-------------------------------------------------------------------------
-PRBool nsWindow::OnResize(nsRect &aWindowRect)
+PRBool nsWindow::OnResize(nsIntRect &aWindowRect)
 {
   // call the event callback
   if (mEventCallback) {
@@ -6002,7 +6001,7 @@ PRBool nsWindow::DispatchMouseEvent(PRUint32 aEventType, WPARAM wParam,
     return result;
   }
 
-  nsPoint eventPoint;
+  nsIntPoint eventPoint;
   eventPoint.x = GET_X_LPARAM(lParam);
   eventPoint.y = GET_Y_LPARAM(lParam);
 
@@ -6011,7 +6010,7 @@ PRBool nsWindow::DispatchMouseEvent(PRUint32 aEventType, WPARAM wParam,
                      ? nsMouseEvent::eContextMenuKey
                      : nsMouseEvent::eNormal);
   if (aEventType == NS_CONTEXTMENU && aIsContextMenuKey) {
-    nsPoint zero(0, 0);
+    nsIntPoint zero(0, 0);
     InitEvent(event, &zero);
   } else {
     InitEvent(event, &eventPoint);
@@ -6023,8 +6022,8 @@ PRBool nsWindow::DispatchMouseEvent(PRUint32 aEventType, WPARAM wParam,
   event.isAlt     = IS_VK_DOWN(NS_VK_ALT);
   event.button    = aButton;
 
-  nsRect mpWidget;
-  nsRect mpScreen;
+  nsIntRect mpWidget;
+  nsIntRect mpScreen;
   mpWidget.x = eventPoint.x;
   mpWidget.y = eventPoint.y;
   WidgetToScreen(mpWidget, mpScreen);
@@ -6171,7 +6170,7 @@ PRBool nsWindow::DispatchMouseEvent(PRUint32 aEventType, WPARAM wParam,
       if (nsToolkit::gMouseTrailer && !mIsInMouseCapture) {
         nsToolkit::gMouseTrailer->SetMouseTrailerWindow(mWnd);
       }
-      nsRect rect;
+      nsIntRect rect;
       GetBounds(rect);
       rect.x = 0;
       rect.y = 0;
@@ -6215,7 +6214,7 @@ PRBool nsWindow::DispatchMouseEvent(PRUint32 aEventType, WPARAM wParam,
 //
 //-------------------------------------------------------------------------
 #ifdef ACCESSIBILITY
-PRBool nsWindow::DispatchAccessibleEvent(PRUint32 aEventType, nsIAccessible** aAcc, nsPoint* aPoint)
+PRBool nsWindow::DispatchAccessibleEvent(PRUint32 aEventType, nsIAccessible** aAcc, nsIntPoint* aPoint)
 {
   PRBool result = PR_FALSE;
 
@@ -6459,7 +6458,7 @@ nsWindow::HandleTextEvent(HIMC hIMEContext,PRBool aCheckAttr)
     return;
 
   nsTextEvent event(PR_TRUE, NS_TEXT_TEXT, this);
-  nsPoint point(0, 0);
+  nsIntPoint point(0, 0);
 
   InitEvent(event, &point);
 
@@ -6486,7 +6485,7 @@ nsWindow::HandleTextEvent(HIMC hIMEContext,PRBool aCheckAttr)
   //
   if (event.theReply.mCursorPosition.width || event.theReply.mCursorPosition.height)
   {
-    nsRect cursorPosition;
+    nsIntRect cursorPosition;
     ResolveIMECaretPos(event.theReply.mReferenceWidget,
                        event.theReply.mCursorPosition,
                        this, cursorPosition);
@@ -6552,7 +6551,7 @@ nsWindow::HandleStartComposition(HIMC hIMEContext)
     return PR_TRUE;
 
   nsCompositionEvent event(PR_TRUE, NS_COMPOSITION_START, this);
-  nsPoint point(0, 0);
+  nsIntPoint point(0, 0);
   CANDIDATEFORM candForm;
 
   InitEvent(event, &point);
@@ -6563,7 +6562,7 @@ nsWindow::HandleStartComposition(HIMC hIMEContext)
   //
   if (event.theReply.mCursorPosition.width || event.theReply.mCursorPosition.height)
   {
-    nsRect cursorPosition;
+    nsIntRect cursorPosition;
     ResolveIMECaretPos(event.theReply.mReferenceWidget,
                        event.theReply.mCursorPosition,
                        this, cursorPosition);
@@ -6615,7 +6614,7 @@ nsWindow::HandleEndComposition(void)
     return;
 
   nsCompositionEvent event(PR_TRUE, NS_COMPOSITION_END, this);
-  nsPoint point(0, 0);
+  nsIntPoint point(0, 0);
 
   if (gPinYinIMECaretCreated)
   {
@@ -7090,7 +7089,7 @@ PRBool nsWindow::OnIMEReconvert(LPARAM aData, LRESULT *oResult)
   RECONVERTSTRING* pReconv = (RECONVERTSTRING*) aData;
 
   nsQueryContentEvent selection(PR_TRUE, NS_QUERY_SELECTED_TEXT, this);
-  nsPoint point(0, 0);
+  nsIntPoint point(0, 0);
   InitEvent(selection, &point);
   DispatchWindowEvent(&selection);
   if (!selection.mSucceeded)
@@ -7146,7 +7145,7 @@ PRBool nsWindow::OnIMEQueryCharPosition(LPARAM aData, LRESULT *oResult)
       pCharPosition->dwCharPos > len)
     return PR_FALSE;
 
-  nsPoint point(0, 0);
+  nsIntPoint point(0, 0);
 
   nsQueryContentEvent selection(PR_TRUE, NS_QUERY_SELECTED_TEXT, this);
   InitEvent(selection, &point);
@@ -7157,7 +7156,7 @@ PRBool nsWindow::OnIMEQueryCharPosition(LPARAM aData, LRESULT *oResult)
   PRUint32 offset = selection.mReply.mOffset + pCharPosition->dwCharPos;
   PRBool useCaretRect = selection.mReply.mString.IsEmpty();
 
-  nsRect r;
+  nsIntRect r;
   if (!useCaretRect) {
     nsQueryContentEvent charRect(PR_TRUE, NS_QUERY_CHARACTER_RECT, this);
     charRect.InitForQueryCharacterRect(offset);
@@ -7179,7 +7178,7 @@ PRBool nsWindow::OnIMEQueryCharPosition(LPARAM aData, LRESULT *oResult)
     r = caretRect.mReply.mRect;
   }
 
-  nsRect screenRect;
+  nsIntRect screenRect;
   // We always need top level window that is owner window of the popup window
   // even if the content of the popup window has focus.
   ResolveIMECaretPos(GetTopLevelWindow(PR_FALSE), r, nsnull, screenRect);
@@ -7198,9 +7197,9 @@ PRBool nsWindow::OnIMEQueryCharPosition(LPARAM aData, LRESULT *oResult)
 //==========================================================================
 void
 nsWindow::ResolveIMECaretPos(nsIWidget* aReferenceWidget,
-                             nsRect&    aCursorRect,
+                             nsIntRect& aCursorRect,
                              nsIWidget* aNewOriginWidget,
-                             nsRect&    aOutRect)
+                             nsIntRect& aOutRect)
 {
   aOutRect = aCursorRect;
 
diff --git a/widget/src/windows/nsWindow.h b/widget/src/windows/nsWindow.h
index 044825194dec..776feb3afa31 100644
--- a/widget/src/windows/nsWindow.h
+++ b/widget/src/windows/nsWindow.h
@@ -129,14 +129,14 @@ public:
 
   // nsIWidget interface
   NS_IMETHOD              Create(nsIWidget *aParent,
-                                 const nsRect &aRect,
+                                 const nsIntRect &aRect,
                                  EVENT_CALLBACK aHandleEventFunction,
                                  nsIDeviceContext *aContext,
                                  nsIAppShell *aAppShell = nsnull,
                                  nsIToolkit *aToolkit = nsnull,
                                  nsWidgetInitData *aInitData = nsnull);
   NS_IMETHOD              Create(nsNativeWidget aParent,
-                                 const nsRect &aRect,
+                                 const nsIntRect &aRect,
                                  EVENT_CALLBACK aHandleEventFunction,
                                  nsIDeviceContext *aContext,
                                  nsIAppShell *aAppShell = nsnull,
@@ -147,7 +147,7 @@ public:
   // Create(nsNativeWidget...)
 
   virtual nsresult        StandardWindowCreate(nsIWidget *aParent,
-                                               const nsRect &aRect,
+                                               const nsIntRect &aRect,
                                                EVENT_CALLBACK aHandleEventFunction,
                                                nsIDeviceContext *aContext,
                                                nsIAppShell *aAppShell,
@@ -171,9 +171,9 @@ public:
   NS_IMETHOD              Enable(PRBool aState);
   NS_IMETHOD              IsEnabled(PRBool *aState);
   NS_IMETHOD              SetFocus(PRBool aRaise);
-  NS_IMETHOD              GetBounds(nsRect &aRect);
-  NS_IMETHOD              GetClientBounds(nsRect &aRect);
-  NS_IMETHOD              GetScreenBounds(nsRect &aRect);
+  NS_IMETHOD              GetBounds(nsIntRect &aRect);
+  NS_IMETHOD              GetClientBounds(nsIntRect &aRect);
+  NS_IMETHOD              GetScreenBounds(nsIntRect &aRect);
   NS_IMETHOD              SetBackgroundColor(const nscolor &aColor);
   NS_IMETHOD              SetCursor(nsCursor aCursor);
   NS_IMETHOD              SetCursor(imgIContainer* aCursor,
@@ -181,22 +181,22 @@ public:
   NS_IMETHOD              HideWindowChrome(PRBool aShouldHide);
   NS_IMETHOD              Validate();
   NS_IMETHOD              Invalidate(PRBool aIsSynchronous);
-  NS_IMETHOD              Invalidate(const nsRect & aRect, PRBool aIsSynchronous);
+  NS_IMETHOD              Invalidate(const nsIntRect & aRect, PRBool aIsSynchronous);
   NS_IMETHOD              InvalidateRegion(const nsIRegion *aRegion, PRBool aIsSynchronous);
   NS_IMETHOD              Update();
   virtual void*           GetNativeData(PRUint32 aDataType);
   virtual void            FreeNativeData(void * data, PRUint32 aDataType);//~~~
   NS_IMETHOD              SetColorMap(nsColorMap *aColorMap);
   //XXX-Scroll is obsolete it is going away soon
-  NS_IMETHOD              Scroll(PRInt32 aDx, PRInt32 aDy, nsRect *aClipRect);
+  NS_IMETHOD              Scroll(PRInt32 aDx, PRInt32 aDy, nsIntRect *aClipRect);
   NS_IMETHOD              ScrollWidgets(PRInt32 aDx, PRInt32 aDy);
-  NS_IMETHOD              ScrollRect(nsRect &aRect, PRInt32 aDx, PRInt32 aDy);
+  NS_IMETHOD              ScrollRect(nsIntRect &aRect, PRInt32 aDx, PRInt32 aDy);
   NS_IMETHOD              SetTitle(const nsAString& aTitle);
   NS_IMETHOD              SetIcon(const nsAString& aIconSpec);
   NS_IMETHOD              SetMenuBar(void * aMenuBar) { return NS_ERROR_FAILURE; }
   NS_IMETHOD              ShowMenuBar(PRBool aShow)         { return NS_ERROR_FAILURE; }
-  NS_IMETHOD              WidgetToScreen(const nsRect& aOldRect, nsRect& aNewRect);
-  NS_IMETHOD              ScreenToWidget(const nsRect& aOldRect, nsRect& aNewRect);
+  NS_IMETHOD              WidgetToScreen(const nsIntRect& aOldRect, nsIntRect& aNewRect);
+  NS_IMETHOD              ScreenToWidget(const nsIntRect& aOldRect, nsIntRect& aNewRect);
   NS_IMETHOD              BeginResizingChildren(void);
   NS_IMETHOD              EndResizingChildren(void);
   NS_IMETHOD              GetPreferredSize(PRInt32& aWidth, PRInt32& aHeight);
@@ -256,15 +256,15 @@ public:
                                              PRBool aIsContextMenuKey = PR_FALSE,
                                              PRInt16 aButton = nsMouseEvent::eLeftButton);
 #ifdef ACCESSIBILITY
-  virtual PRBool          DispatchAccessibleEvent(PRUint32 aEventType, nsIAccessible** aAccessible, nsPoint* aPoint = nsnull);
+  virtual PRBool          DispatchAccessibleEvent(PRUint32 aEventType, nsIAccessible** aAccessible, nsIntPoint* aPoint = nsnull);
   already_AddRefed<nsIAccessible> GetRootAccessible();
 #endif
   virtual PRBool          AutoErase();
-  nsPoint*                GetLastPoint() { return &mLastPoint; }
+  nsIntPoint*             GetLastPoint() { return &mLastPoint; }
 
   PRInt32                 GetNewCmdMenuId() { mMenuCmdId++; return mMenuCmdId; }
 
-  void                    InitEvent(nsGUIEvent& event, nsPoint* aPoint = nsnull);
+  void                    InitEvent(nsGUIEvent& event, nsIntPoint* aPoint = nsnull);
 
   void                    SuppressBlurEvents(PRBool aSuppress);
   PRBool                  BlurEventsSuppressed();
@@ -314,7 +314,7 @@ protected:
   virtual void            OnDestroy();
   virtual PRBool          OnMove(PRInt32 aX, PRInt32 aY);
   virtual PRBool          OnPaint(HDC aDC = nsnull);
-  virtual PRBool          OnResize(nsRect &aWindowRect);
+  virtual PRBool          OnResize(nsIntRect &aWindowRect);
   
   void                    SetupModKeyState();
   BOOL                    OnChar(UINT charCode, UINT aScanCode, PRUint32 aFlags = 0);
@@ -355,9 +355,9 @@ protected:
    *  @param aOutRect         The converted cursor rect.
    */
   void                    ResolveIMECaretPos(nsIWidget* aReferenceWidget,
-                                             nsRect&    aCursorRect,
+                                             nsIntRect& aCursorRect,
                                              nsIWidget* aNewOriginWidget,
-                                             nsRect&    aOutRect);
+                                             nsIntRect& aOutRect);
 
   virtual PRBool          DispatchKeyEvent(PRUint32 aEventType, WORD aCharCode,
                             const nsTArray<nsAlternativeCharCode>* aAlternativeChars,
@@ -379,7 +379,7 @@ protected:
   PRBool DispatchCommandEvent(PRUint32 aEventCommand);
   void RelayMouseEvent(UINT aMsg, WPARAM wParam, LPARAM lParam);
 
-  void GetNonClientBounds(nsRect &aRect);
+  void GetNonClientBounds(nsIntRect &aRect);
   void HandleTextEvent(HIMC hIMEContext, PRBool aCheckAttr=PR_TRUE);
   BOOL HandleStartComposition(HIMC hIMEContext);
   void HandleEndComposition(void);
@@ -429,9 +429,9 @@ protected:
 
   static TriStateBool sCanQuit;
 
-  nsSize        mLastSize;
+  nsIntSize     mLastSize;
   static        nsWindow* gCurrentWindow;
-  nsPoint       mLastPoint;
+  nsIntPoint    mLastPoint;
   HWND          mWnd;
   HDC           mPaintDC; // only set during painting
 #if 0
diff --git a/widget/src/xpwidgets/nsBaseDragService.cpp b/widget/src/xpwidgets/nsBaseDragService.cpp
index 889cc32d410c..be17402a7100 100644
--- a/widget/src/xpwidgets/nsBaseDragService.cpp
+++ b/widget/src/xpwidgets/nsBaseDragService.cpp
@@ -401,7 +401,7 @@ nsresult
 nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
                             nsIScriptableRegion* aRegion,
                             PRInt32 aScreenX, PRInt32 aScreenY,
-                            nsRect* aScreenDragRect,
+                            nsIntRect* aScreenDragRect,
                             gfxASurface** aSurface,
                             nsPresContext** aPresContext)
 {
@@ -441,10 +441,11 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
       // the region's coordinates are relative to the root frame
       nsIFrame* rootFrame = presShell->GetRootFrame();
       if (rootFrame && *aPresContext) {
-        nsRect dragRect;
+        nsIntRect dragRect;
         aRegion->GetBoundingBox(&dragRect.x, &dragRect.y, &dragRect.width, &dragRect.height);
-        dragRect.ScaleRoundOut(nsPresContext::AppUnitsPerCSSPixel());
-        dragRect.ScaleRoundOut(1.0 / (*aPresContext)->AppUnitsPerDevPixel());
+        dragRect = nsRect::ToOutsidePixels(nsIntRect::ToAppUnits(dragRect,
+                                                                 nsPresContext::AppUnitsPerCSSPixel()),
+                                           (*aPresContext)->AppUnitsPerDevPixel());
 
         nsIntRect screenRect = rootFrame->GetScreenRectExternal();
         aScreenDragRect->SetRect(screenRect.x + dragRect.x, screenRect.y + dragRect.y,
@@ -468,7 +469,7 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
 
   // draw the image for selections
   if (mSelection) {
-    nsPoint pnt(aScreenDragRect->x, aScreenDragRect->y);
+    nsIntPoint pnt(aScreenDragRect->x, aScreenDragRect->y);
     nsRefPtr<gfxASurface> surface = presShell->RenderSelection(mSelection, pnt, aScreenDragRect);
     *aSurface = surface;
     NS_IF_ADDREF(*aSurface);
@@ -498,7 +499,7 @@ nsBaseDragService::DrawDrag(nsIDOMNode* aDOMNode,
   if (aRegion)
     aRegion->GetRegion(getter_AddRefs(clipRegion));
 
-  nsPoint pnt(aScreenDragRect->x, aScreenDragRect->y);
+  nsIntPoint pnt(aScreenDragRect->x, aScreenDragRect->y);
   nsRefPtr<gfxASurface> surface = presShell->RenderNode(dragNode, clipRegion,
                                                         pnt, aScreenDragRect);
 
@@ -520,7 +521,7 @@ nsBaseDragService::DrawDragForImage(nsPresContext* aPresContext,
                                     nsIImageLoadingContent* aImageLoader,
                                     nsICanvasElement* aCanvas,
                                     PRInt32 aScreenX, PRInt32 aScreenY,
-                                    nsRect* aScreenDragRect,
+                                    nsIntRect* aScreenDragRect,
                                     gfxASurface** aSurface)
 {
   nsCOMPtr<nsIImage> img;
@@ -559,9 +560,9 @@ nsBaseDragService::DrawDragForImage(nsPresContext* aPresContext,
     aScreenDragRect->height = height;
   }
 
-  nsRect srcRect = *aScreenDragRect;
+  nsIntRect srcRect = *aScreenDragRect;
   srcRect.MoveTo(0, 0);
-  nsRect destRect = srcRect;
+  nsIntRect destRect = srcRect;
 
   if (destRect.width == 0 || destRect.height == 0)
     return NS_ERROR_FAILURE;
diff --git a/widget/src/xpwidgets/nsBaseDragService.h b/widget/src/xpwidgets/nsBaseDragService.h
index 442be9ef5b55..f17e06550409 100644
--- a/widget/src/xpwidgets/nsBaseDragService.h
+++ b/widget/src/xpwidgets/nsBaseDragService.h
@@ -103,7 +103,7 @@ protected:
   nsresult DrawDrag(nsIDOMNode* aDOMNode,
                     nsIScriptableRegion* aRegion,
                     PRInt32 aScreenX, PRInt32 aScreenY,
-                    nsRect* aScreenDragRect,
+                    nsIntRect* aScreenDragRect,
                     gfxASurface** aSurface,
                     nsPresContext **aPresContext);
 
@@ -115,7 +115,7 @@ protected:
                             nsIImageLoadingContent* aImageLoader,
                             nsICanvasElement* aCanvas,
                             PRInt32 aScreenX, PRInt32 aScreenY,
-                            nsRect* aScreenDragRect,
+                            nsIntRect* aScreenDragRect,
                             gfxASurface** aSurface);
 
   /**
diff --git a/widget/src/xpwidgets/nsBaseWidget.cpp b/widget/src/xpwidgets/nsBaseWidget.cpp
index 01a46159cb97..2657d818058f 100644
--- a/widget/src/xpwidgets/nsBaseWidget.cpp
+++ b/widget/src/xpwidgets/nsBaseWidget.cpp
@@ -145,7 +145,7 @@ nsBaseWidget::~nsBaseWidget()
 //
 //-------------------------------------------------------------------------
 void nsBaseWidget::BaseCreate(nsIWidget *aParent,
-                              const nsRect &aRect,
+                              const nsIntRect &aRect,
                               EVENT_CALLBACK aHandleEventFunction,
                               nsIDeviceContext *aContext,
                               nsIAppShell *aAppShell,
@@ -591,7 +591,7 @@ NS_IMETHODIMP nsBaseWidget::MakeFullScreen(PRBool aFullScreen)
 
   if (aFullScreen) {
     if (!mOriginalBounds)
-      mOriginalBounds = new nsRect();
+      mOriginalBounds = new nsIntRect();
     GetScreenBounds(*mOriginalBounds);
 
     // Move to top-left corner of screen and size to the screen dimensions
@@ -739,7 +739,7 @@ NS_METHOD nsBaseWidget::AddEventListener(nsIEventListener * aListener)
 * If the implementation of nsWindow supports borders this method MUST be overridden
 *
 **/
-NS_METHOD nsBaseWidget::GetClientBounds(nsRect &aRect)
+NS_METHOD nsBaseWidget::GetClientBounds(nsIntRect &aRect)
 {
   return GetBounds(aRect);
 }
@@ -748,7 +748,7 @@ NS_METHOD nsBaseWidget::GetClientBounds(nsRect &aRect)
 * If the implementation of nsWindow supports borders this method MUST be overridden
 *
 **/
-NS_METHOD nsBaseWidget::GetBounds(nsRect &aRect)
+NS_METHOD nsBaseWidget::GetBounds(nsIntRect &aRect)
 {
   aRect = mBounds;
   return NS_OK;
@@ -759,7 +759,7 @@ NS_METHOD nsBaseWidget::GetBounds(nsRect &aRect)
 * this method must be overridden
 *
 **/
-NS_METHOD nsBaseWidget::GetScreenBounds(nsRect &aRect)
+NS_METHOD nsBaseWidget::GetScreenBounds(nsIntRect &aRect)
 {
   return GetBounds(aRect);
 }
@@ -768,7 +768,7 @@ NS_METHOD nsBaseWidget::GetScreenBounds(nsRect &aRect)
 * 
 *
 **/
-NS_METHOD nsBaseWidget::SetBounds(const nsRect &aRect)
+NS_METHOD nsBaseWidget::SetBounds(const nsIntRect &aRect)
 {
   mBounds = aRect;
 
@@ -783,8 +783,8 @@ NS_METHOD nsBaseWidget::SetBounds(const nsRect &aRect)
 **/
 NS_METHOD nsBaseWidget::GetBorderSize(PRInt32 &aWidth, PRInt32 &aHeight)
 {
-  nsRect rectWin;
-  nsRect rect;
+  nsIntRect rectWin;
+  nsIntRect rect;
   GetBounds(rectWin);
   GetClientBounds(rect);
 
@@ -799,7 +799,7 @@ NS_IMETHODIMP nsBaseWidget::ScrollWidgets(PRInt32 aDx, PRInt32 aDy)
   return NS_ERROR_FAILURE;
 }
 
-NS_IMETHODIMP nsBaseWidget::ScrollRect(nsRect &aRect, PRInt32 aDx, PRInt32 aDy)
+NS_IMETHODIMP nsBaseWidget::ScrollRect(nsIntRect &aRect, PRInt32 aDx, PRInt32 aDy)
 {
   return NS_ERROR_FAILURE;
 }
@@ -1250,7 +1250,7 @@ nsBaseWidget::debug_DumpPaintEvent(FILE *                aFileOut,
 /* static */ void
 nsBaseWidget::debug_DumpInvalidate(FILE *                aFileOut,
                                    nsIWidget *           aWidget,
-                                   const nsRect *        aRect,
+                                   const nsIntRect *     aRect,
                                    PRBool                aIsSynchronous,
                                    const nsCAutoString & aWidgetName,
                                    PRInt32               aWindowID)
diff --git a/widget/src/xpwidgets/nsBaseWidget.h b/widget/src/xpwidgets/nsBaseWidget.h
index e15d1b9fd55c..b4d2b035dd3a 100644
--- a/widget/src/xpwidgets/nsBaseWidget.h
+++ b/widget/src/xpwidgets/nsBaseWidget.h
@@ -118,12 +118,12 @@ public:
   NS_IMETHOD              SetWindowClass(const nsAString& xulWinType);
   NS_IMETHOD              SetBorderStyle(nsBorderStyle aBorderStyle); 
   NS_IMETHOD              AddEventListener(nsIEventListener * aListener);
-  NS_IMETHOD              SetBounds(const nsRect &aRect);
-  NS_IMETHOD              GetBounds(nsRect &aRect);
-  NS_IMETHOD              GetClientBounds(nsRect &aRect);
-  NS_IMETHOD              GetScreenBounds(nsRect &aRect);
+  NS_IMETHOD              SetBounds(const nsIntRect &aRect);
+  NS_IMETHOD              GetBounds(nsIntRect &aRect);
+  NS_IMETHOD              GetClientBounds(nsIntRect &aRect);
+  NS_IMETHOD              GetScreenBounds(nsIntRect &aRect);
   NS_IMETHOD              GetBorderSize(PRInt32 &aWidth, PRInt32 &aHeight);
-  NS_IMETHOD              ScrollRect(nsRect &aRect, PRInt32 aDx, PRInt32 aDy);
+  NS_IMETHOD              ScrollRect(nsIntRect &aRect, PRInt32 aDx, PRInt32 aDy);
   NS_IMETHOD              ScrollWidgets(PRInt32 aDx, PRInt32 aDy);
   NS_IMETHOD              EnableDragDrop(PRBool aEnable);
   NS_IMETHOD              GetAttention(PRInt32 aCycleCount);
@@ -153,7 +153,7 @@ protected:
                                           nsILocalFile **aResult);
   virtual void            OnDestroy();
   virtual void            BaseCreate(nsIWidget *aParent,
-                                     const nsRect &aRect,
+                                     const nsIntRect &aRect,
                                      EVENT_CALLBACK aHandleEventFunction,
                                      nsIDeviceContext *aContext,
                                      nsIAppShell *aAppShell,
@@ -188,8 +188,8 @@ protected:
   PRPackedBool      mIsAltDown;
   PRPackedBool      mIsDestroying;
   PRPackedBool      mOnDestroyCalled;
-  nsRect            mBounds;
-  nsRect*           mOriginalBounds;
+  nsIntRect         mBounds;
+  nsIntRect*        mOriginalBounds;
   PRInt32           mZIndex;
   nsSizeMode        mSizeMode;
 
@@ -216,7 +216,7 @@ protected:
 
   static void debug_DumpInvalidate(FILE *                aFileOut,
                                    nsIWidget *           aWidget,
-                                   const nsRect *        aRect,
+                                   const nsIntRect *     aRect,
                                    PRBool                aIsSynchronous,
                                    const nsCAutoString & aWidgetName,
                                    PRInt32               aWindowID);
diff --git a/widget/src/xpwidgets/nsPrintOptionsImpl.cpp b/widget/src/xpwidgets/nsPrintOptionsImpl.cpp
index ec1626f8396c..31f4a7fe868e 100644
--- a/widget/src/xpwidgets/nsPrintOptionsImpl.cpp
+++ b/widget/src/xpwidgets/nsPrintOptionsImpl.cpp
@@ -38,7 +38,6 @@
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsPrintOptionsImpl.h"
-#include "nsCoord.h"
 #include "nsReadableUtils.h"
 #include "nsPrintSettingsImpl.h"
 
@@ -252,9 +251,8 @@ nsPrintOptions::ReadPrefs(nsIPrintSettings* aPS, const nsAString& aPrinterName,
   NS_ENSURE_ARG_POINTER(aPS);
 
   if (aFlags & nsIPrintSettings::kInitSaveMargins) {
-    nscoord halfInch = NS_INCHES_TO_TWIPS(0.5);
-    nsMargin margin;
-    margin.SizeTo(halfInch, halfInch, halfInch, halfInch);
+    PRInt32 halfInch = NS_INCHES_TO_TWIPS(0.5);
+    nsIntMargin margin(halfInch, halfInch, halfInch, halfInch);
     ReadInchesToTwipsPref(GetPrefName(kMarginTop, aPrinterName), margin.top,
                           kMarginTop);
     DUMP_INT(kReadStr, kMarginTop, margin.top);
@@ -271,8 +269,7 @@ nsPrintOptions::ReadPrefs(nsIPrintSettings* aPS, const nsAString& aPrinterName,
   }
 
   if (aFlags & nsIPrintSettings::kInitSaveEdges) {
-    nsMargin margin;
-    margin.SizeTo(0,0,0,0);
+    nsIntMargin margin(0,0,0,0);
     ReadInchesIntToTwipsPref(GetPrefName(kEdgeTop, aPrinterName), margin.top,
                              kEdgeTop);
     DUMP_INT(kReadStr, kEdgeTop, margin.top);
@@ -289,8 +286,7 @@ nsPrintOptions::ReadPrefs(nsIPrintSettings* aPS, const nsAString& aPrinterName,
   }
 
   if (aFlags & nsIPrintSettings::kInitSaveUnwriteableMargins) {
-    nsMargin margin;
-    margin.SizeTo(0,0,0,0);
+    nsIntMargin margin;
     ReadInchesIntToTwipsPref(GetPrefName(kUnwriteableMarginTop, aPrinterName), margin.top,
                              kUnwriteableMarginTop);
     DUMP_INT(kReadStr, kUnwriteableMarginTop, margin.top);
@@ -558,7 +554,7 @@ nsPrintOptions::WritePrefs(nsIPrintSettings *aPS, const nsAString& aPrinterName,
   NS_ENSURE_ARG_POINTER(aPS);
   NS_ENSURE_STATE(mPrefBranch);
 
-  nsMargin margin;
+  nsIntMargin margin;
   if (aFlags & nsIPrintSettings::kInitSaveMargins) {
     if (NS_SUCCEEDED(aPS->GetMarginInTwips(margin))) {
       WriteInchesFromTwipsPref(GetPrefName(kMarginTop, aPrinterName),
@@ -576,7 +572,7 @@ nsPrintOptions::WritePrefs(nsIPrintSettings *aPS, const nsAString& aPrinterName,
     }
   }
 
-  nsMargin edge;
+  nsIntMargin edge;
   if (aFlags & nsIPrintSettings::kInitSaveEdges) {
     if (NS_SUCCEEDED(aPS->GetEdgeInTwips(edge))) {
       WriteInchesIntFromTwipsPref(GetPrefName(kEdgeTop, aPrinterName),
@@ -594,7 +590,7 @@ nsPrintOptions::WritePrefs(nsIPrintSettings *aPS, const nsAString& aPrinterName,
     }
   }
 
-  nsMargin unwriteableMargin;
+  nsIntMargin unwriteableMargin;
   if (aFlags & nsIPrintSettings::kInitSaveUnwriteableMargins) {
     if (NS_SUCCEEDED(aPS->GetUnwriteableMarginInTwips(unwriteableMargin))) {
       WriteInchesIntFromTwipsPref(GetPrefName(kUnwriteableMarginTop, aPrinterName),
@@ -1170,7 +1166,7 @@ nsPrintOptions::WritePrefDouble(const char * aPrefId, double aVal)
 }
 
 void
-nsPrintOptions::ReadInchesToTwipsPref(const char * aPrefId, nscoord& aTwips,
+nsPrintOptions::ReadInchesToTwipsPref(const char * aPrefId, PRInt32& aTwips,
                                       const char * aMarginPref)
 {
   if (!mPrefBranch) {
@@ -1196,7 +1192,7 @@ nsPrintOptions::ReadInchesToTwipsPref(const char * aPrefId, nscoord& aTwips,
 }
 
 void
-nsPrintOptions::WriteInchesFromTwipsPref(const char * aPrefId, nscoord aTwips)
+nsPrintOptions::WriteInchesFromTwipsPref(const char * aPrefId, PRInt32 aTwips)
 {
   if (!mPrefBranch) {
     return;
@@ -1210,7 +1206,7 @@ nsPrintOptions::WriteInchesFromTwipsPref(const char * aPrefId, nscoord aTwips)
 }
 
 void
-nsPrintOptions::ReadInchesIntToTwipsPref(const char * aPrefId, nscoord& aTwips,
+nsPrintOptions::ReadInchesIntToTwipsPref(const char * aPrefId, PRInt32& aTwips,
                                          const char * aMarginPref)
 {
   if (!mPrefBranch) {
@@ -1230,7 +1226,7 @@ nsPrintOptions::ReadInchesIntToTwipsPref(const char * aPrefId, nscoord& aTwips,
 }
 
 void
-nsPrintOptions::WriteInchesIntFromTwipsPref(const char * aPrefId, nscoord aTwips)
+nsPrintOptions::WriteInchesIntFromTwipsPref(const char * aPrefId, PRInt32 aTwips)
 {
   if (!mPrefBranch) {
     return;
diff --git a/widget/src/xpwidgets/nsPrintOptionsImpl.h b/widget/src/xpwidgets/nsPrintOptionsImpl.h
index 15c07367a581..53e01e5c288a 100644
--- a/widget/src/xpwidgets/nsPrintOptionsImpl.h
+++ b/widget/src/xpwidgets/nsPrintOptionsImpl.h
@@ -76,12 +76,12 @@ protected:
   void ReadJustification(const char * aPrefId, PRInt16& aJust,
                          PRInt16 aInitValue);
   void WriteJustification(const char * aPrefId, PRInt16 aJust);
-  void ReadInchesToTwipsPref(const char * aPrefId, nscoord&  aTwips,
+  void ReadInchesToTwipsPref(const char * aPrefId, PRInt32&  aTwips,
                              const char * aMarginPref);
-  void WriteInchesFromTwipsPref(const char * aPrefId, nscoord aTwips);
-  void ReadInchesIntToTwipsPref(const char * aPrefId, nscoord&  aTwips,
+  void WriteInchesFromTwipsPref(const char * aPrefId, PRInt32 aTwips);
+  void ReadInchesIntToTwipsPref(const char * aPrefId, PRInt32&  aTwips,
                                 const char * aMarginPref);
-  void WriteInchesIntFromTwipsPref(const char * aPrefId, nscoord aTwips);
+  void WriteInchesIntFromTwipsPref(const char * aPrefId, PRInt32 aTwips);
 
   nsresult ReadPrefString(const char * aPrefId, nsAString& aString);
   /**
diff --git a/widget/src/xpwidgets/nsPrintSettingsImpl.cpp b/widget/src/xpwidgets/nsPrintSettingsImpl.cpp
index 5487d5a1cc34..8bb6288d9324 100644
--- a/widget/src/xpwidgets/nsPrintSettingsImpl.cpp
+++ b/widget/src/xpwidgets/nsPrintSettingsImpl.cpp
@@ -36,7 +36,6 @@
  * ***** END LICENSE BLOCK ***** */
 
 #include "nsPrintSettingsImpl.h"
-#include "nsCoord.h"
 #include "nsReadableUtils.h"
 #include "nsIPrintSession.h"
 
@@ -82,7 +81,7 @@ nsPrintSettings::nsPrintSettings() :
 {
 
   /* member initializers and constructor code */
-  nscoord marginWidth = NS_INCHES_TO_TWIPS(DEFAULT_MARGIN_WIDTH);
+  PRInt32 marginWidth = NS_INCHES_TO_TWIPS(DEFAULT_MARGIN_WIDTH);
   mMargin.SizeTo(marginWidth, marginWidth, marginWidth, marginWidth);
   mEdge.SizeTo(0, 0, 0, 0);
   mUnwriteableMargin.SizeTo(0,0,0,0);
@@ -1004,14 +1003,14 @@ NS_IMETHODIMP nsPrintSettings::SetPaperData(PRInt16 aPaperData)
  *	@update 1/12/01 rods
  */
 NS_IMETHODIMP 
-nsPrintSettings::SetMarginInTwips(nsMargin& aMargin)
+nsPrintSettings::SetMarginInTwips(nsIntMargin& aMargin)
 {
   mMargin = aMargin;
   return NS_OK;
 }
 
 NS_IMETHODIMP 
-nsPrintSettings::SetEdgeInTwips(nsMargin& aEdge)
+nsPrintSettings::SetEdgeInTwips(nsIntMargin& aEdge)
 {
   mEdge = aEdge;
   return NS_OK;
@@ -1021,7 +1020,7 @@ nsPrintSettings::SetEdgeInTwips(nsMargin& aEdge)
 // to check for negative margin values in aUnwriteableMargin (which 
 // would indicate that we should use the system default unwriteable margin.)
 NS_IMETHODIMP 
-nsPrintSettings::SetUnwriteableMarginInTwips(nsMargin& aUnwriteableMargin)
+nsPrintSettings::SetUnwriteableMarginInTwips(nsIntMargin& aUnwriteableMargin)
 {
   if (aUnwriteableMargin.top >= 0) {
     mUnwriteableMargin.top = aUnwriteableMargin.top;
@@ -1043,21 +1042,21 @@ nsPrintSettings::SetUnwriteableMarginInTwips(nsMargin& aUnwriteableMargin)
  *	@update 6/21/00 dwc
  */
 NS_IMETHODIMP 
-nsPrintSettings::GetMarginInTwips(nsMargin& aMargin)
+nsPrintSettings::GetMarginInTwips(nsIntMargin& aMargin)
 {
   aMargin = mMargin;
   return NS_OK;
 }
 
 NS_IMETHODIMP 
-nsPrintSettings::GetEdgeInTwips(nsMargin& aEdge)
+nsPrintSettings::GetEdgeInTwips(nsIntMargin& aEdge)
 {
   aEdge = mEdge;
   return NS_OK;
 }
 
 NS_IMETHODIMP 
-nsPrintSettings::GetUnwriteableMarginInTwips(nsMargin& aUnwriteableMargin)
+nsPrintSettings::GetUnwriteableMarginInTwips(nsIntMargin& aUnwriteableMargin)
 {
   aUnwriteableMargin = mUnwriteableMargin;
   return NS_OK;
diff --git a/widget/src/xpwidgets/nsPrintSettingsImpl.h b/widget/src/xpwidgets/nsPrintSettingsImpl.h
index ed9805a0d1d6..4cbce17d2e4f 100644
--- a/widget/src/xpwidgets/nsPrintSettingsImpl.h
+++ b/widget/src/xpwidgets/nsPrintSettingsImpl.h
@@ -82,9 +82,9 @@ protected:
   nsWeakPtr     mSession; // Should never be touched by Clone or Assign
  
   // mMargin, mEdge, and mUnwriteableMargin are stored in twips
-  nsMargin      mMargin;
-  nsMargin      mEdge;
-  nsMargin      mUnwriteableMargin;
+  nsIntMargin   mMargin;
+  nsIntMargin   mEdge;
+  nsIntMargin   mUnwriteableMargin;
 
   PRInt32       mPrintOptions;
 
diff --git a/xpfe/appshell/src/nsWebShellWindow.cpp b/xpfe/appshell/src/nsWebShellWindow.cpp
index b3243a3db4b8..ccb5267b7fcd 100644
--- a/xpfe/appshell/src/nsWebShellWindow.cpp
+++ b/xpfe/appshell/src/nsWebShellWindow.cpp
@@ -182,7 +182,7 @@ nsresult nsWebShellWindow::Initialize(nsIXULWindow* aParent,
   
   // XXX: need to get the default window size from prefs...
   // Doesn't come from prefs... will come from CSS/XUL/RDF
-  nsRect r(0, 0, aInitialWidth, aInitialHeight);
+  nsIntRect r(0, 0, aInitialWidth, aInitialHeight);
   
   // Create top level window
   mWindow = do_CreateInstance(kWindowCID, &rv);
diff --git a/xpfe/appshell/src/nsXULWindow.cpp b/xpfe/appshell/src/nsXULWindow.cpp
index a5351ac0a7fd..d602e5762fda 100644
--- a/xpfe/appshell/src/nsXULWindow.cpp
+++ b/xpfe/appshell/src/nsXULWindow.cpp
@@ -616,7 +616,7 @@ NS_IMETHODIMP nsXULWindow::SetPositionAndSize(PRInt32 aX, PRInt32 aY,
 NS_IMETHODIMP nsXULWindow::GetPositionAndSize(PRInt32* x, PRInt32* y, PRInt32* cx,
    PRInt32* cy)
 {
-  nsRect rect;
+  nsIntRect rect;
 
   if (!mWindow)
     return NS_ERROR_FAILURE;