Bug 255584. Don't include areas above and to the left of the origin when we're trying to figure out the scrollable width and height --- we can't scroll to them! r+sr=dbaron

layout/generic/nsGfxScrollFrame.cpp

@@ -2132,11 +2132,14 @@ nsGfxScrollFrameInner::GetScrolledSize(nsPresContext* aPresContext,
   mScrollAreaBox->GetChildBox(&child);
   nsIFrame* frame;
   child->GetFrame(&frame);
+
   nsIView* view = frame->GetView();
   NS_ASSERTION(view,"Scrolled frame must have a view!!!");
   
   nsRect rect = view->GetBounds();
-  nsSize size(rect.width, rect.height);
+  // forget about the stuff above or to the left of the origin, since
+  // we can't currently scroll there anyway.
+  nsSize size(rect.XMost(), rect.YMost());
  
   nsBox::AddMargin(child, size);
   nsBox::AddBorderAndPadding(mScrollAreaBox, size);

layout/html/base/src/nsGfxScrollFrame.cpp

@@ -2132,11 +2132,14 @@ nsGfxScrollFrameInner::GetScrolledSize(nsPresContext* aPresContext,
   mScrollAreaBox->GetChildBox(&child);
   nsIFrame* frame;
   child->GetFrame(&frame);
+
   nsIView* view = frame->GetView();
   NS_ASSERTION(view,"Scrolled frame must have a view!!!");
   
   nsRect rect = view->GetBounds();
-  nsSize size(rect.width, rect.height);
+  // forget about the stuff above or to the left of the origin, since
+  // we can't currently scroll there anyway.
+  nsSize size(rect.XMost(), rect.YMost());
  
   nsBox::AddMargin(child, size);
   nsBox::AddBorderAndPadding(mScrollAreaBox, size);

layout/xul/base/src/nsBoxToBlockAdaptor.cpp

@@ -897,15 +897,19 @@ nsBoxToBlockAdaptor::Reflow(nsBoxLayoutState& aState,
     // we will set the child's rect to include the overflow size.
        if (mFrame->GetStateBits() & NS_FRAME_OUTSIDE_CHILDREN) {
          // make sure we store the overflow size
-         mOverflow.width  = aDesiredSize.mOverflowArea.width;
-         mOverflow.height = aDesiredSize.mOverflowArea.height;
+
+         // This kinda sucks. We should be able to handle the case
+         // where there's overflow above or to the left of the
+         // origin. But for now just chop that stuff off.
+         mOverflow.width  = aDesiredSize.mOverflowArea.XMost();
+         mOverflow.height = aDesiredSize.mOverflowArea.YMost();
 
          // include the overflow size in our child's rect?
          if (mIncludeOverflow) {
              //printf("OutsideChildren width=%d, height=%d\n", aDesiredSize.mOverflowArea.width, aDesiredSize.mOverflowArea.height);
-             aDesiredSize.width = aDesiredSize.mOverflowArea.width;
+             aDesiredSize.width = aDesiredSize.mOverflowArea.XMost();
              if (aDesiredSize.width <= aWidth)
-               aDesiredSize.height = aDesiredSize.mOverflowArea.height;
+               aDesiredSize.height = aDesiredSize.mOverflowArea.YMost();
              else {
               if (aDesiredSize.width > aWidth)
               {
@@ -922,7 +926,7 @@ nsBoxToBlockAdaptor::Reflow(nsBoxLayoutState& aState,
                  mFrame->WillReflow(aPresContext);
                  mFrame->Reflow(aPresContext, aDesiredSize, reflowState, aStatus);
                  if (mFrame->GetStateBits() & NS_FRAME_OUTSIDE_CHILDREN)
-                    aDesiredSize.height = aDesiredSize.mOverflowArea.height;
+                   aDesiredSize.height = aDesiredSize.mOverflowArea.YMost();
 
               }
              }