[ Thanks to An
Anonymous Reader for this link. ]
“Today, while toying around with the system settings menu in KDE
4.5, I noticed an option to enable the good old Ctrl+Alt+Backspace
combo. It’s been a while since I’ve used that combination thanks to
the stability KDE offers these days and, it wasn’t until I
discovered it in the settings that I remembered using it a few
years back. The combo, which allowed killing the X server is now
disabled by default in many major Linux distributions.“The combination is simple, just press Ctrl+Alt+Backspace
together and your X server gets restarted taking you back to the
login screen. It might not be that useful for normal users but it
can be quite helpful for beta testers. Here’s how to enable
it.”