I’m running Debian with KDE, and I recently upgraded from Debian 11 (running Plasma 5.20) to Debian 12 (running Plasma 5.27). I have two monitors.
I’m experiencing an annoying regression after this upgrade: pressing the Meta key used to open the Application Launcher consistently, but now, it only does so if a window on my primary monitor is focused.
(To be more precise, it only does so if a window on the same monitor as the taskbar is focused. If I move the taskbar to my secondary monitor, now the Meta key works to activate the Application Launcher on my secondary monitor, but not my primary monitor.)
Based on some research, the Meta key opening the Application Launcher is something that should Just Work in Plasma 5.8+ as long as there is some shortcut assigned to the Application Launcher (in my case, Alt+F1 is assigned, and that does work on both monitors). (I can’t seem to link to things, but I’m basing this specifically on the “Windows/Meta Key” section of the “Plasma/Tips” page of the KDE UserBase Wiki.) And it does Just Work – but only on one monitor, as described.
Any suggestions for what might be going wrong, or how to diagnose this further?
I’ve been thinking about what may be causing this, and I have a theory:
If I’m remembering correctly, when I first logged into my desktop session after the upgrade to Debian 12, my taskbar was gone, and I had to rebuild it (i.e. create a new panel and populate it with components like the Application Launcher, Task Manager, etc.)
So perhaps the old taskbar is still on the books somewhere (just hidden / offscreen or something), and that’s what’s responding to the Meta key when the focus is not on the monitor with the visible taskbar?
Is there a way to track down / clean up such hidden / “ghost” panels?
1. Searched ~/.config/plasma-org.kde.plasma.desktop-appletsrc for config groups mentioning org.kde.plasma.kickoff. Somehow, I had no fewer than four!
2. After backing up ~/.config/plasma-org.kde.plasma.desktop-appletsrc, removed all config groups mentioning org.kde.plasma.kickoff, including other child config groups with the same group name as prefix.
3. Restarted plasmashell with systemctl --user restart plasma-plasmashell.service to pick up the changes from the previous step. This had the (expected) effect that my Application Launcher widget was gone.
4. Added a new Application Launcher widget to my taskbar, which can now be activated successfully with the Meta key from either monitor.
Thank you very much to @jpetso for suggesting diagnostic steps and ultimately this solution offline!