Comment 26 for bug 49613

Created attachment 169650
revised patch against trunk

One of the things I am unsure of is how I am obtaining the drawable:

nsObjectFrame.cpp
 exposeEvent.drawable = (Drawable)win->GetNativeData(NS_NATIVE_WIDGET);

So maybe others who have worked on this patch or know layout internals better
can collaborate.

I'll post a revised test case next.