http://bugs.winehq.org/show_bug.cgi?id=22356
--- Comment #6 from Roderick Colenbrander thunderbird2k@gmail.com 2010-04-22 06:30:51 --- I have seen the issue on Nvidia and I know what the problem is. The patch itself was not bad but the problem is that some other piece of code is removing the SFLAG_CONVERTED flag. Before we always set it by hand, so that hid this issue.
The problem in this case appears to be flip_surface which swaps surface flags (evil). I'm thinking what the nicest fix is.