http://bugs.winehq.org/show_bug.cgi?id=23180
--- Comment #16 from Andreas Hermann Braml andreas@braml.org 2010-06-25 10:45:27 --- A workaround is to uncheck that the window manager should control the windows in the graphics settings with winecfg.
I would report the bug to KWin next. Although I can give a description of the sympthoms of the bug and insert a link to here, I don't have any insight into what part of their window management stuff doesn't work as expected.
Should I post the link to the report on bugs.kde.org so that you could give them more specific information, as time permits? Or would you prefer to file the bug yourself, giving them the more general description of the problem at hand right from the start?
One way or another, it would be great if you could lend a hand in further triaging this beast ;)