Hey Erich,
on OSX I also get this with pix_snap, but I think it is that the bgcolour of the gemwin is set to alpha when copied with pix_snap. With pix_snap2tex things act "normal" that is the background colour is copied along with the other pixels with full opacity. I'm (also?) catitolizing on this "feature" in self-similar and so I hope it would stick around!
I have no tried this on linux in some time...
B.
Erich Berger wrote:
the attached patch is a texture feedback with pix_alpha in a manner that black becomes alpha.