http://bugs.winehq.org/show_bug.cgi?id=24222
--- Comment #3 from LCID Fire lcid-fire@gmx.net 2010-08-31 12:23:38 CDT --- (In reply to comment #1)
Does support Mutter the dialog type windows?
Try to disable _NET_WM_WINDOW_TYPE_DIALOG in dlls/winex11.drv/window.c and see if that helps.
Outcommented all setting of dialog and still not displaying.