Package xorg-xephyr: Information

Xephyr is a kdrive based X Server which targets a window on
a host X Server as its framebuffer. Unlike Xnest it supports
modern X extensions (even if host server doesn't) such as Composite,
Damage, randr etc.

It uses SHM Images and shadow framebuffer updates to provide
good performance.
It also has a visual debugging mode for observing screen updates.