http://bugs.winehq.org/show_bug.cgi?id=22356
--- Comment #19 from Roderick Colenbrander thunderbird2k@gmail.com 2010-04-28 09:59:35 --- Created an attachment (id=27599) --> (http://bugs.winehq.org/attachment.cgi?id=27599) The real fix ;)
After some more searching it appeared that the actual issue is that read_from_framebuffer_texture is allocating the texture (because nothing else did it before) but it doesn't set the conversion flags. Instead use surface_prepare_texture to allocate the texture.