Bug 130078. Reverting fix because of regressions. We'll have to come back to this again :-(.

layout/base/nsCSSRendering.cpp

@@ -2795,20 +2795,21 @@ nsCSSRendering::PaintBackground(nsPresContext* aPresContext,
   if (canvasColor.mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) {
     nsIView* rootView;
     vm->GetRootView(rootView);
-    PRBool useDefaultBackgroundColor = rootView->IsUsingDefaultBackgroundColor();
+    if (!rootView->GetParent()) {
-    if (!rootView->GetParent() && rootView->HasWidget()) {
+      PRBool widgetIsTranslucent = PR_FALSE;
-      PRBool widgetIsTranslucent;
+
+      if (rootView->HasWidget()) {
         rootView->GetWidget()->GetWindowTranslucency(widgetIsTranslucent);
-      useDefaultBackgroundColor = !widgetIsTranslucent;
       }
       
-    if (useDefaultBackgroundColor) {
+      if (!widgetIsTranslucent) {
         // Ensure that we always paint a color for the root (in case there's
         // no background at all or a partly transparent image).
         canvasColor.mBackgroundFlags &= ~NS_STYLE_BG_COLOR_TRANSPARENT;
         canvasColor.mBackgroundColor = aPresContext->DefaultBackgroundColor();
       }
     }
+  }
 
   vm->SetDefaultBackgroundColor(canvasColor.mBackgroundColor);
 

layout/base/nsDisplayList.cpp

@@ -502,23 +502,14 @@ nsDisplayBackground::IsOpaque(nsDisplayListBuilder* aBuilder) {
 
   PRBool isCanvas;
   const nsStyleBackground* bg;
-  nsPresContext* presContext = mFrame->GetPresContext();
   PRBool hasBG =
-  nsCSSRendering::FindBackground(presContext, mFrame, &bg, &isCanvas);
+    nsCSSRendering::FindBackground(mFrame->GetPresContext(), mFrame, &bg, &isCanvas);
-  if (!hasBG)
+  if (!hasBG || (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) ||
+      bg->mBackgroundClip != NS_STYLE_BG_CLIP_BORDER ||
+      HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius) ||
+      NS_GET_A(bg->mBackgroundColor) < 255)
     return PR_FALSE;
-  PRBool isTranslucentColor = NS_GET_A(bg->mBackgroundColor) < 255 ||
+  return PR_TRUE;
-    (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT);
-  if (isCanvas) {
-    nsIView* rootView;
-    presContext->GetViewManager()->GetRootView(rootView);
-    if (rootView->IsUsingDefaultBackgroundColor()) {
-      isTranslucentColor = NS_GET_A(presContext->DefaultBackgroundColor()) < 255;
-    }
-  }
-  return !isTranslucentColor &&
-    bg->mBackgroundClip == NS_STYLE_BG_CLIP_BORDER &&
-    !HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius);  
 }
 
 PRBool

layout/base/nsDocumentViewer.cpp

@@ -2331,29 +2331,45 @@ DocumentViewerImpl::MakeWindow(nsIWidget* aParentWidget,
   tbounds.y = 0;
 
   // Create a child window of the parent that is our "root view/window"
+  // if aParentWidget has a view, we'll hook our view manager up to its view tree
   nsIView* containerView = nsView::GetViewFor(aParentWidget);
 
+  if (containerView) {
+    // see if the containerView has already been hooked into a foreign view manager hierarchy
+    // if it has, then we have to hook into the hierarchy too otherwise bad things will happen.
+    nsIViewManager* containerVM = containerView->GetViewManager();
+    nsIView* pView = containerView;
+    do {
+      pView = pView->GetParent();
+    } while (pView && pView->GetViewManager() == containerVM);
+
+    if (!pView) {
+      // OK, so the container is not already hooked up into a foreign view manager hierarchy.
+      // That means we can choose not to hook ourselves up.
+      //
+      // If the parent container is a chrome shell then we won't hook into its view
+      // tree. This will improve performance a little bit (especially given scrolling/painting perf bugs)
+      // but is really just for peace of mind. This check can be removed if we want to support fancy
+      // chrome effects like transparent controls floating over content, transparent Web browsers, and
+      // things like that, and the perf bugs are fixed.
+      nsCOMPtr<nsIDocShellTreeItem> container(do_QueryReferent(mContainer));
+      nsCOMPtr<nsIDocShellTreeItem> parentContainer;
+      PRInt32 itemType;
+      if (nsnull == container
+          || NS_FAILED(container->GetParent(getter_AddRefs(parentContainer)))
+          || nsnull == parentContainer
+          || NS_FAILED(parentContainer->GetItemType(&itemType))
+          || itemType != nsIDocShellTreeItem::typeContent) {
+        containerView = nsnull;
+      }
+    }
+  }
+
   // Create a view
   nsIView* view = mViewManager->CreateView(tbounds, containerView);
   if (!view)
     return NS_ERROR_OUT_OF_MEMORY;
 
-  if (containerView) {
-    nsCOMPtr<nsIDocShellTreeItem> container(do_QueryReferent(mContainer));
-    nsCOMPtr<nsIDocShellTreeItem> parentContainer;
-    PRInt32 itemType;
-    PRInt32 parentItemType;
-    if (container
-        && NS_SUCCEEDED(container->GetItemType(&itemType))
-        && itemType == nsIDocShellTreeItem::typeContent
-        && NS_SUCCEEDED(container->GetParent(getter_AddRefs(parentContainer)))
-        && parentContainer
-        && NS_SUCCEEDED(parentContainer->GetItemType(&parentItemType))
-        && parentItemType != nsIDocShellTreeItem::typeContent) {
-      view->SetUseDefaultBackgroundColor(PR_TRUE);
-    }
-  }
-
   // pass in a native widget to be the parent widget ONLY if the view hierarchy will stand alone.
   // otherwise the view will find its own parent widget and "do the right thing" to
   // establish a parent/child widget relationship

view/public/nsIView.h

@@ -90,8 +90,6 @@ enum nsViewVisibility {
 // is z-index:auto also
 #define NS_VIEW_FLAG_TOPMOST              0x0010
 
-#define NS_VIEW_FLAG_USE_DEFAULT_BACKGROUND 0x0020
-
 struct nsViewZIndex {
   PRBool mIsAuto;
   PRInt32 mZIndex;
@@ -285,18 +283,6 @@ public:
     return mVFlags & NS_VIEW_FLAG_UNIFORM_BACKGROUND;
   }
 
-  void SetUseDefaultBackgroundColor(PRBool aUseDefault) {
-    if (aUseDefault) {
-      mVFlags |= NS_VIEW_FLAG_USE_DEFAULT_BACKGROUND;
-    } else {
-      mVFlags &= ~NS_VIEW_FLAG_USE_DEFAULT_BACKGROUND;
-    }
-  }
-
-  PRBool IsUsingDefaultBackgroundColor() {
-    return mVFlags & NS_VIEW_FLAG_USE_DEFAULT_BACKGROUND;
-  }
-  
   /**
    * Set the view's link to client owned data.
    * @param aData - data to associate with view. nsnull to disassociate