Comment 14 for bug 1024208

Progress update:
In the linked branch above I can fake the clipping on the pixel shader as follows: instead of clipping polygons in view space I discard the pixels that would be clipped by the planes in the fragment shader. The shaders have been tested and work with the fixed function pipeline 3d windows implementation.

TODO:
In order to have clipping in GLES2 I need to modify the compiz shader system (see opengl plugin) to accept clipping planes and re-write the td function to use GLES2 compatible code. This is in progress but it's not a priority so, be patient...

The 3d windows work OK on the desktop.