- Added support for 32 bit surfaces when it's possible (use of Xrender extension..).
- Modified the Cairo backend to take advantage of that: we can now draw windows with partial transparency.
- Fixed a bug in the Cairo backend (copy of a surface to itself) using the cairo "groups". Scrolling is still wrong, but we're closer to something good ;-)
git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/back/trunk@25441 72102866-910b-0410-8b05-ffd578937521
