http://bugs.winehq.org/show_bug.cgi?id=22627
--- Comment #4 from Alexandros Karatarakis danimothonline@gmail.com 2010-06-04 19:20:49 --- Ok, so i read bug 15881 and it seems that pressing F6 or F7 usually only once will indeed solve the problem! Very nice workaround and it means you won't have to alt-f4 out of the game.
I noticed however a problem. This ONLY works when i have desktop effects ENABLED. This is pretty weird since usually desktop effects mess something up. I couldn't not get out of the black screen when desktop effect were set to none(ubuntu 10.04).
I am not sure i understand your second paragraph. What i observe in fullscreen is that the game is indeed fullscreen but i can see the gnome taskbars (top & bottom) overlapping the edges of the fullscreen game.
Finally, i can do a regression testing but i am not sure what to look for at this point. Emperor has a constantly changing behaviour in recent versions(by recent i mean going back to ~1.1.18 where i started maintaining emperor). Come to think of it, you mention 1.1.18 had a functioning fullscreen so i will try dissecting to see what broken that.