SUMMARY Changing primary display moves the panels on those displays. For example if we have Screen 1 and Screen 2. On login, Screen 2 is set to the primary display. Changing Screen 1 to the primary display will swap the panels on these screens. STEPS TO REPRODUCE Changing the primary display and the panels will be swapped. OBSERVED RESULT Changing which display is set as the Primary display will cause the panels to be swapped. A semi-unrelated side note: If the panel is being swapped from a non-scaled display to a scaled display, the icons will also appear blurry. Hovering over them resolves this. EXPECTED RESULT Settings primary output will not affect panel setup. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.16.0-arch1-1 KDE Plasma Version: 5.23.90 KDE Frameworks Version: 5.90.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION This bug is particularly a pain because dragging panels too quickly between displays causes a crash. This is a separate bug that I believe is already being tracked, but I wanted to mention a more critical reason as to why just swapping the panels is a real headache.
This seems to also swap the wallpapers between the displays.
>Changing which display is set as the Primary display will cause the panels to be swapped. Yes. That's the primary purpose of the primary display flag. Why else are you setting it?
I assumed the purpose of a primary display was to have things like game windows open on that display primarily, as well as notification bubbles, and things like KRunner and Application Dashboard appearing on that display. Those are my own personal expectations of what a primary display flag would do, I would not have expected it to change the setup of my panels or wallpapers.