Comment 9 for bug 910539

Although I agree with both points. It is hard coded limit in X11, and you can hit it with NVIDIA drivers. However, in this case, there is a bug in the ATI drivers which causes users to hit this limit sooner due to elevated number of windows created and/or not released correctly.

Wayland *should* resolve this issue, however, ATI drivers would need to be coded to use that driver format as they are currently not supported.