http://bugs.winehq.org/show_bug.cgi?id=52
--- Comment #18 from Alexandre Julliard julliard@winehq.org 2008-02-06 13:35:14 --- This is a partial WONTFIX. We can't prevent other X11 apps from drawing, as that would require grabbing the X server and that's not something we want to allow a Windows app to do.
We could prevent other Windows apps from drawing by implementing LockWindowUpdate, so that part is a valid bug. But it means the behavior will then only be guaranteed to be correct in desktop mode.