switching session after locking, doesn't close the switch session window

[AL13N]

Hi i'm a Mageia contributor, and i have an issue with switching sessions (in 
4.11.4) (not on the list, please keep me in CC)

requirements:
2 users, each a KDE session running (locked)

What happens is:
1) lock session
2) click "swich user" button
3) from the list, click on the other session
4) click activate
5) (this dialog doesn't close)
6) i get to the lock screen of the 2nd session
7) i can unlock it and do stuff
8) i lock that session
9) click "switch user" button
10) from the list, click on the first session
11) click activate to get back to the first session
12) when getting back and moving mouse to remove screensaver, the switch 
session window is still open, making it unclear if you actually switched, and 
annoying cause you have to cancel that window, to be able to unlock that first 
one

(of course, if you now switch back to the second session, you get that too and 
there appears that switch session window again)


after looking at the code, i don't see where it actually closes this window?

https://projects.kde.org/projects/kde/kde-workspace/repository/revisions/v4.10.5/entry/ksmserver/screenlocker/greeter/sessions.cpp#L147