http://bugs.winehq.org/show_bug.cgi?id=10982
--- Comment #22 from Vincent Povirk madewokherd@gmail.com 2009-10-08 18:19:27 --- Patch sent for PNG encoding: http://www.winehq.org/pipermail/wine-patches/2009-October/079703.html
ClearScale should work after this patch.