Comment 6 for bug 941060

For headless testing I sometimes use Xvfb on DISPLAY :99. Then I may or may not launch a lightweight Windows Manager like fluxbox or awesome, x11vnc, xload, and noninteractive web browser for automation.

However sometimes to view or interact to debug my apps, I start Xephyr on :99 instead of Xvfb (after starting Xwindows on :0 the usual way with whatever session, gnome/unity/etc.)

This may have affected fluxbox since Xephyr unlike Xvfb cannot survive without its parent Xserver, or if the Xserver at :0 is having driver issues.