http://bugs.winehq.org/show_bug.cgi?id=20164
--- Comment #10 from Roderick Colenbrander thunderbird2k@gmail.com 2009-09-27 05:48:12 --- Version 7 doesn't have the issue. If you can please analyze the code a bit and figure out where it goes wrong. In short all the function does is copying data from a source pixmap (which has an associated xrender picture) to a destination. Either something is wrong with masking or perhaps as you say with offsets.
Roderick