However, I feel this shortcut is very useful and is a lifesaver in several situations.
If you want to enable this shortcut then either you have to edit the xorg.conf file or install a command named dontzap.
To install this package search in synaptic for package named dontzap or issue following command.
sudo apt-get install dontzap
Once you have installed this package, type following command in terminal to enable this X11 keyboard shortcut.
sudo dontzap --disable
For some reason, If you want to disable this shortcut again, then either modify the xorg.conf manually or issue following command,
sudo dontzap --enable
That's it folks.