That's not entirely complete. When working with a non-local X server, XSHM would not be available. I think most users would be okay with degraded performance under such cases, but I think we should try and not break things completely.The systems without XSHM would be native Windows..������ Linux,������ BSD, Solaris,������ and Mac with X installed are all good to go..
It will even run on android with X installed.