[Bug 9875] moving dialogs shows artifacts on window behind it

http://bugs.winehq.org/show_bug.cgi?id=9875

--- Comment #1 from Clinton Stimpson   2007-10-08 10:51:30 ---
The basic painting sequence of the family view is (from debug trace):

BeginPaint()
  ....
  ShowWindow(button1, hide / show);
  RedrawWindow(button1, ...);
  ...
  ValidateRect(self, ...);
EndPaint();

In the call to RedrawWindow, X server Expose events are sometimes consumed, and
the update region is modified.  But the call to ValidateRect() is clearing
those update regions so they never get painted.

This can be fixed by not filtering for Expose events on QS_PAINT in
winex11.drv/event.c's filter_event function.