http://bugs.winehq.org/show_bug.cgi?id=15118
--- Comment #43 from Joshua wine@placesthroughtime.com 2012-09-08 11:02:36 CDT --- (In reply to comment #40)
Created attachment 40848 [details] Partial fix for Diablo III layered window issue
See if the attached patch makes a difference, it's only a partial fix for Diablo III - but it's possible that it fixes the issue if all the involved windows are controlled by Wine. If the patch fixes the issue then Bug #22090 should probably be considered a duplicate of this bug.
Atleast for me that patch made the background/transparent area white instead of black and modified the behavior of mouseover effects with the World of Warcraft launcher, which uses the same effects as the Diablo III and Starcraft II launchers use as well.