Bug 453510

Unclear to me if `ksmserver` is the actual component to report this issue against or if the issue is elsewhere.

The plasma desktop provides a Switch User option that is quite dangerous.

If you select that functionality and you do not have another user to log in as, then you are locked out of your machine.

In fact:

- I you select `switch user`, you are presented with a login screen and *there is no way* to go back.
- If you have a single user or you do not know the credentials of other users, the only thing you can do at this point is to try to log in with your credentials
- If you do so, a new session is opened with the same username as one that was already open and this locks up plasma.

This should not happen.

a) If you select `switch user`, there should always be a cancel button.
b) If you try to log in again as the same user and the same session type, this should be recognized and the existing session should be used, rather than trying to start a new session for the same user and the same desktop type, which cannot work.


STEPS TO REPRODUCE
1. Login to plasma
2. Select Switch User from the menu
3. Try to get back to work by entering your credentials

OBSERVED RESULT

KDE locks up


EXPECTED RESULT

KDE should never lock up and prevent situations causing it to lock up.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Manjaro Linux 
KDE Plasma Version: 5.24.4
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.3