http://bugs.winehq.org/show_bug.cgi?id=26693
--- Comment #9 from Dmitry Timoshkov dmitry@codeweavers.com 2011-04-12 09:28:41 CDT --- The problem is that Metacity ignores the transient_for hint if the window owner is a fullscreen window, it places the fullscreen window on top of the owned window. Somehow dialog type changes internal WM semantics and compensates for that Metacity bug.