SUMMARY In multi-display configuration, you can select different desktop wallpapers for each display. You can't do that from lock screen appearance configuration. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 6.1.0 KDE Frameworks Version: 6.3.0 Qt Version: 6.7.1 Kernel Version: 6.9.5-arch1-1 (64-bit) Graphics Platform: X11
Indeed, it's just one for all.
Is it only KCM issue? KCMs for desktop wallpaper and lock screen appearance look very similar but can you actually use different wallpapers in kscreenlocker? That will be different from just adding display selector to KCM.
This is particular an issue if the two screens have different aspect ratios. I can prepare a wallpaper that looks well on one screen, but then it will look bad on the other (and the reverse). I already tried different "positioning" settings to workaround this, but no luck. For the desktop background wallpaper ("Appearance & Style > Wallpaper") I took a 16:10 image and show it as-is on the 16:10 screen. For the 21:9 screen I cropped a 21:9 section out of it, so the picture looks well on both screens. I would like to do the same for "Security & Privacy > Screen Locking". (Ideally I could set the screenlocker background setting to always follow the desktop wallpaper setting, but that's a different feature request.)