Bug 389224: Clipped objects are sometimes not fully redrawn after clipping. r+sr=roc, a=dbaron

layout/generic/nsAbsoluteContainingBlock.cpp

@@ -423,12 +423,12 @@ nsAbsoluteContainingBlock::ReflowAbsoluteFrame(nsIFrame*                aDelegat
 
   if (oldRect.TopLeft() != rect.TopLeft() || 
       (aDelegatingFrame->GetStateBits() & NS_FRAME_FIRST_REFLOW) ||
-      ((aKidFrame->GetStyleDisplay()->mClipFlags & NS_STYLE_CLIP_RECT) && 
-       (kidDesiredSize.mOverflowArea != oldOverflowRect))) {
+      (kidDesiredSize.mOverflowArea + rect.TopLeft() != oldOverflowRect &&
+        (kidDesiredSize.mOverflowArea + rect.TopLeft() != rect || oldRect != oldOverflowRect))) {
     // The frame moved; we have to invalidate the whole frame
     // because the children may have moved after they were reflowed
-    // We also have to invalidate when we're clipping and the overflow
-    // changes; the style code doesn't know how to deal with this case
+    // We also have to invalidate when we have overflow and the overflow
+    // changes because the change might be caused by clipping
     // XXX This could be optimized in some cases, especially clipping changes
     aKidFrame->GetParent()->Invalidate(oldOverflowRect);
     aKidFrame->GetParent()->Invalidate(kidDesiredSize.mOverflowArea +

layout/style/nsStyleStruct.cpp

@@ -1169,11 +1169,6 @@ nsChangeHint nsStyleDisplay::CalcDifference(const nsStyleDisplay& aOther) const
 
   if (mClipFlags != aOther.mClipFlags || mClip != aOther.mClip) {
     NS_UpdateHint(hint, nsChangeHint_ReflowFrame);
-    // The reflow code in naAbsoluteContainingBlock can deal with invalidation
-    // in all cases except changing from non-auto clip to auto clip; when
-    // changing to auto clip, the frame can't tell what happened
-    if (mClipFlags == NS_STYLE_CLIP_AUTO)
-      NS_UpdateHint(hint, nsChangeHint_RepaintFrame);
   }
   // XXX the following is conservative, for now: changing float breaking shouldn't
   // necessarily require a repaint, reflow should suffice.