The new XRender code uses 21 times less cpu than the old
read-back-and-manually-blend option. The blending is also
GPU-accelerated where possible, but works in software on
vesa/fb drivers.
git-svn-id: file:///fltk/svn/fltk/branches/branch-1.3@10630 ea41ed52-d2ee-0310-a9c1-e6b18d33e121
