Q: How to disable Ctrl+Alt+Backspace from restarting X in GNOME?

1. Read General Notes

2. sudo cp /etc/X11/xorg.conf /etc/X11/xorg.conf_backup
   sudo gedit /etc/X11/xorg.conf

3. Append the following lines at the end of file

   Section "ServerFlags"
   	Option		"DontZap"		"yes"
   EndSection

4. Save the edited file (sample)
5. Read How to restart GNOME without rebooting computer?