The problem is that there are TWO places where this is set.
In the setup tool, there is Workspace/Desktop Behavior/Screen Locking - where I can say "Lock screen automatically after:" then enter a time in minutes.
This does not work worth a damn. I can lock the screen manually - but not have it happen automatically.
However, hidden away under Hardware/Power Management/Energy Saving - there is "Screen Energy Saving" and "Switch off after"...which DOES work.
It's not quite the same thing though because it doesn't lock the screen - and it literally turns the video off rather than displaying a blank screen (or whatever) but for me, it's "good enough".
Screen savers no longer exist without you installing a bunch of extra stuff. So your lock screen (if you can get it to work) won't be any of the cool animations we used to have.
There are two settings. The screen locking and screen switch off.
If I want both locking and switch off, it is necessary to switch off the screen after screen locking. Otherwise the lock screen will wake up the screen, which leads to burn-in of the screen (more accurately, image persistence). What works for me is:
Desktop Behavior → Screen Locking → Activation → Lock screen automatically after → 10 mins
Power management → Energy Saving → Screen Energy Saving → Switch off after → 15 mins
This specific behavior may be influenced by my proprietary NVIDIA driver.
Look at System Settings → Desktop Behavior.
Re. a screensaver, that's not included by default because modern screens aren't affected.
But, if you're interested, look at Where are the screensavers.
I have Kubuntu 18.04 - with nVidia drivers..
The problem is that there are TWO places where this is set.
In the setup tool, there is Workspace/Desktop Behavior/Screen Locking - where I can say "Lock screen automatically after:" then enter a time in minutes.
This does not work worth a damn. I can lock the screen manually - but not have it happen automatically.
However, hidden away under Hardware/Power Management/Energy Saving - there is "Screen Energy Saving" and "Switch off after"...which DOES work.
It's not quite the same thing though because it doesn't lock the screen - and it literally turns the video off rather than displaying a blank screen (or whatever) but for me, it's "good enough".
Screen savers no longer exist without you installing a bunch of extra stuff. So your lock screen (if you can get it to work) won't be any of the cool animations we used to have.
There are two settings. The screen locking and screen switch off.
If I want both locking and switch off, it is necessary to switch off the screen after screen locking. Otherwise the lock screen will wake up the screen, which leads to burn-in of the screen (more accurately, image persistence). What works for me is:
This specific behavior may be influenced by my proprietary NVIDIA driver.
Actually you can find the screen locking on the Energy section of System Preferences.There you could choose the locking behavior and many more.
I hope you know that Ctrl+Alt+L locks the display window.
The screen saver option was answered by DK Bose.
In kUbuntu 20.04 look at System Settings → Screen Locking.
There is no System Settings → Desktop Behavior in my system.