From Fedora Project Wiki
Luminocity
About
Luminocity is a toy compositing manager and window manager written using OpenGL. Rather than displaying on the X server that it is managing, it opens an OpenGL window on a separate server. This allows rapid development, since you can simply run lumonicity within your normal X session pointed at a headless X server. When you make a code change, you can simply restart luminocity, and your test setup is preserved.
http://fishsoup.net/blog_images/Luminocity-3-small.jpg
Download
Luminocity is available in GNOME CVS as the luminocity module. The easiest way to build it and it's dependencies is
using jhbuild .