CTRL+ALT+BACKSPACE to work again

When upgraded to Ubuntu 9.04 Jaunty I found that the CTRL+ALT+BACKSPACE - which restarts the X-server at problems - no longer working. I used a second X server before at instable applications or games, where just pressed these keys and the whole thing closed, and I was able to go back to my normal desktop, and even if there was a problem I restarted just the X. Here is the way, how to enable again this function:

Edit the /etc/X11/xorg.conf, and put the disable dontzap option into the serverflags section:

Section "ServerFlags"
Option "DontZap" "false"
EndSection