As of yesterday, when I leave my laptop and return after a while, when I touch the mouse/keyboard the screensaver is turned off but I'm left with a screen with only the default wallpaper and a mouse cursor. Noticably missing is the unlock dialog, since the system is locked. Luckily, I've found a workaround that allows me to return to the session without a hard restart - going into terminal (ctrl-alt-f1), and running killall 'kscreenlocker_greet'. The when I return to the GUI (ctrl-alt-f1) I see the normal unlock dialog, enter the password and it unlocks properly. Reproducible: Always
Typo correction: it's 'killall kscreenlocker_greet', and return to GUI via ctrl-alt-f7. I couldn't find a way to edit the bug description...
Additional info: apparently this happens only when an external monitor is connected to the laptop.
I see this if I try to unlock the screen too soon after it kicks in. If the monitors go off, and I immediately activate the mouse/keyboard, I see exactly what the reporter mentions (desktop background and nothing else), and it takes several minutes before the unlock dialog actually appears. Doesn't happen if it's been a couple of minutes or more than the screen has been locked.
Sounds like a duplicate of bug#329076. I proposed a fix here: https://git.reviewboard.kde.org/r/117091/ *** This bug has been marked as a duplicate of bug 329076 ***