SUMMARY When having the login screen that is prompting for a password, there are 2 independent login screens rendered on each connected monitor (if usually the mode is set to extend the monitor instead of mirroring the main screen at least). For a login screen I think this is a rather weird behavior as this forces be to figure out which of the password prompts is currently having focus. Thus I would propose to mirror the main screen's content to all secondary screens for the login prompt and only start extending the screen after that. STEPS TO REPRODUCE 1. Configure multiple monitors to extend the screen 2. Open login prompt (aka: logout) SOFTWARE/OS VERSIONS Operating System: KDE neon 5.21 KDE Plasma Version: 5.21.1 KDE Frameworks Version: 5.79.0 Qt Version: 5.15.2 Kernel Version: 5.4.0-59-generic OS Type: 64-bit Graphics Platform: X11 Processors: 8 × Intel® Core™ i7-4770 CPU @ 3.40GHz Memory: 15,6 GiB of RAM Graphics Processor: GeForce GTX 660 Ti/PCIe/SSE2
Do you mean the screen locker or the the display manager? the display manager may not apply to plasmashell (is SDDM). SDDM at my setup only has a single screen for login. However, I find this really relevant for the lock screen.
possibly related to Bug 440144
> Do you mean the screen locker or the the display manager? I'm not sure - maybe neither. I am referring to the screen you land on when you just booted your computer and are then prompted to enter your password to log-in
ok, you are talking about the display manager (most likely sddm) in this case. You can setup sddm using xrandr, see here: https://blog.victormendonca.com/2018/06/29/how-to-fix-sddm-on-multiple-screens/ The instructions there do not fully cover your setting, but ist should be fairly simple to use xrandr to mirror the screen. I am re-assingning this bug to the sddm kcm (i.e., the system settings module to configure it). Maybe it is a common use case they can support in their setup.
*** This bug has been marked as a duplicate of bug 390503 ***