For a desktop Linux user like me having the (formerly standard) CTRL ALT Backspace keystroke at hand is one of the great joys in life.
For decades X-windows users have been able to rely on the CTRL ALT BKSP combination to restart their window manager when it locked up. Curse the Gnome developers for wrenching it out of the default Gnome Shell configuration. Bless them for providing the flexibility that allows me to restore it.
The thousand times blessed Gnome Tweak Tool provides an easy way to set this behavior under Typing… Key Sequence to kill the X server. Just select “Control + Alt + Backspace” from the drop down menu (make sure you’ve turned on “Show all installed input sources” at the top of the panel, otherwise you might now see the menu item).
From the command line use setxkbmap:
setxkbmap -option terminate:ctrl_alt_bksp
Go do it now.