http://bugs.winehq.org/show_bug.cgi?id=10142
--- Comment #37 from Steven legitemail@mt2009.com 2009-05-12 10:52:34 --- First, sorry for the snarkiness of my previous comment.
Second, this only happens to me with one (badly behaved?) app, so it might not be the same bug that others are hitting. The behavior is similar, but indeterministic: about 25% of the time when I switch desktops, my wine window will disappear even though it's still running. The window apparently has wonky geometry; another WM reported, "Window manager warning: Window 0x2800011 (Cake Poker) sets an MWM hint indicating it isn't resizable, but sets min size 1 x 1 and max size 2147483647 x 2147483647; this doesn't make much sense."