XFixes: terminate the X server when a specific connection ends
Currently, if a screen locker exits, the screen will be unlocked. This is inherently fragile and caused Qubes Security Bulletin 068.
A much better solution would be for the X server to exit if the screen locker does. This can be accomplished by way of a new extension. When the client requests the extension, the server marks the connection as critical. If a critical connection is closed, the X server exits.
Edited by Peter Hutterer