If there is no way to share pixmaps between display connections then I think we have no choice but to use Unix shared memory and perform texture upload on the compositor side. This will close off Skia-GL, BTW, until we can hack it to remote all GL commands to the other process.

But I'm confused—if you can't share pixmaps between display connections, then how does Compiz work on the NVIDIA driver? I thought you could transform the output of `glxgears`, for example.