Toggle user being listed in login greeter
Offer way to exclude a user being listed in the login greeter. That this completely prevents a user logging in via the greeter is not important. This is for users that are supposed to be hidden from 'over the shoulder browsing' and mostly used via
- An option 'show in login greeter' must be added, which is by default switched on.
- Change of the switch should be stored in a persistent way and user should not be listed in the greeter when the switch is set to off.
- This feature should be tested thoroughly, especially the edge case where no user at all is allowed to be shown in the greeter. Is the system then locked forever? Perhaps, users with sudoer rights should not be able to hide themselves from teh greeter. Needs discussion.