Bug#796957:

[★ <yasuna@gmail.com>]

So, not sure if this is the same bug or not, but it has been annoying
me ever since I switched to KDE5 from KDE4..

When SDDM shows up (for example, when locking the screen), the
password box gains focus initially.. However, if SDDM loses focus for
any reason (for example, a new window appears in KDE), it is literally
impossible to give SDDM focus again using the keyboard.. No keys do
any thing at all.. If you are in a situation where you don't happen to
have a mouse plugged in, you are screwed and have no way of logging
back in to your session.. The only thing you can do is Control+Alt+F1
in to a new terminal and killall SDDM..


I have a simple way to reproduce this bug:

1: In KDE5, open a konsole window, and run this line:

sleep 32 ; kdialog --msgbox "derp"

2: Then, before the 32 seconds is up, lock the screen so that SDDM shows up..

3: Notice how the password box is focused and you can type stuff (but
don't log back in yet)..

4: After the 32 seconds expires, you will notice the password box
loses focus, because the kdialog popped up a new window..

5: Now notice that any and all keys that you attempt to use to regain
focus to SDDM is futile.. There is no way that you can manage to get
focus back to the password box with out resorting to using a mouse..


KDM never had this problem.. The log-in manager is supposed to be a
big shield to your currently running desktop environment, so it almost
seems silly that any application running behind the scenes could steal
back focus from the currently running log-in manager password field..
No one is supposed to have any clue of what is running behind that
log-in manager with out typing in the password..