Bug 762948: Workaround for invalidation problem with flash. r=roc

widget/windows/nsWindow.cpp

@@ -6807,6 +6807,54 @@ nsWindow::SetupKeyModifiersSequence(nsTArray<KeyPair>* aArray, PRUint32 aModifie
   }
 }
 
+static BOOL WINAPI EnumFirstChild(HWND hwnd, LPARAM lParam)
+{
+  *((HWND*)lParam) = hwnd;
+  return FALSE;
+}
+
+static void InvalidatePluginAsWorkaround(nsWindow *aWindow, const nsIntRect &aRect)
+{
+  aWindow->Invalidate(aRect);
+
+  // XXX - Even more evil workaround!! See bug 762948, flash's bottom
+  // level sandboxed window doesn't seem to get our invalidate. We send
+  // an invalidate to it manually. This is totally specialized for this
+  // bug, for other child window structures this will just be a more or
+  // less bogus invalidate but since that should not have any bad
+  // side-effects this will have to do for now.
+  HWND current = (HWND)aWindow->GetNativeData(NS_NATIVE_WINDOW);
+
+  RECT windowRect;
+  RECT parentRect;
+
+  ::GetWindowRect(current, &parentRect);
+        
+  HWND next = current;
+
+  do {
+    current = next;
+
+    ::EnumChildWindows(current, &EnumFirstChild, (LPARAM)&next);
+
+    ::GetWindowRect(next, &windowRect);
+    // This is relative to the screen, adjust it to be relative to the
+    // window we're reconfiguring.
+    windowRect.left -= parentRect.left;
+    windowRect.top -= parentRect.top;
+  } while (next != current && windowRect.top == 0 && windowRect.left == 0);
+
+  if (windowRect.top == 0 && windowRect.left == 0) {
+    RECT rect;
+    rect.left   = aRect.x;
+    rect.top    = aRect.y;
+    rect.right  = aRect.XMost();
+    rect.bottom = aRect.YMost();
+
+    ::InvalidateRect(next, &rect, FALSE);
+  }
+}
+
 nsresult
 nsWindow::ConfigureChildren(const nsTArray<Configuration>& aConfigurations)
 {
@@ -6840,7 +6888,9 @@ nsWindow::ConfigureChildren(const nsTArray<Configuration>& aConfigurations)
         r.Sub(bounds, configuration.mBounds);
         r.MoveBy(-bounds.x,
                  -bounds.y);
-        w->Invalidate(r.GetBounds());
+        nsIntRect toInvalidate = r.GetBounds();
+
+        InvalidatePluginAsWorkaround(w, toInvalidate);
       }
     }
     rv = w->SetWindowClipRegion(configuration.mClipRegion, false);