b=328337, black flash often when repainting areas, r=roc

view/src/nsViewManager.cpp

@@ -1415,6 +1415,11 @@ NS_IMETHODIMP nsViewManager::DispatchEvent(nsGUIEvent *aEvent, nsEventStatus *aS
               // Paint later.
               vm->UpdateView(vm->mRootView, NS_VMREFRESH_NO_SYNC);
               didResize = PR_TRUE;
+
+              // not sure if it's valid for us to claim that we
+              // ignored this, but we're going to do so anyway, since
+              // we didn't actually paint anything
+              *aStatus = nsEventStatus_eIgnore;
             }
           }
 

widget/src/windows/nsWindow.cpp

@@ -4174,7 +4174,12 @@ PRBool nsWindow::ProcessMessage(UINT msg, WPARAM wParam, LPARAM lParam, LRESULT
       break;
 
     case WM_PAINT:
+#ifdef MOZ_CAIRO_GFX
+      *aRetValue = (int) OnPaint();
+      result = PR_TRUE;
+#else
       result = OnPaint();
+#endif
       break;
 
 #ifndef WINCE