Check the update rect, not the region. The region might contain only non-client
parts

Modified: trunk/reactos/subsys/win32k/ntuser/painting.c

--- trunk/reactos/subsys/win32k/ntuser/painting.c	2005-12-04 22:20:50 UTC (rev 19890)
+++ trunk/reactos/subsys/win32k/ntuser/painting.c	2005-12-04 22:28:29 UTC (rev 19891)
@@ -995,7 +995,7 @@

       }
    }
 

-   RETURN(Window->UpdateRegion != NULL);

+   RETURN(!IntGdiIsEmptyRect(&Rect));

 
 CLEANUP:
    DPRINT("Leave NtUserGetUpdateRect, ret=%i\n",_ret_);