SUMMARY In certain cases, a left click on the task bar unexpectedly opens the context menu of a system tray applet that has been used previously. This happens with package-update-indicator (PUI) (https://code.guido-berhoerster.org/projects/package-update-indicator) if its context menu was previously opened with a right click and then closed. According to the developer the bug is not in PUI, but probably in Plasma. STEPS TO REPRODUCE (always reproducible) 1. Install package-update-indicator (tested versions 4 and 5) and start it. It will show in the system tray. 2. Right-click on the PUI systray icon. This opens the PUI context menu (note: left click also opens the menu, but does not trigger the bug). 3. Left-click somewhere on the desktop, but not on the task bar. This closes the PUI context menu. 4. Left-click on the task bar. OBSERVED RESULT The context menu of PUI opens. EXPECTED RESULT Depends on where exactly you clicked, e.g. focus/maximise/minimise the corresponding window, or, if you clicked on empty space, nothing, ... SOFTWARE/OS VERSIONS opensuse Tumbleweed, snapshot 20190829 KDE Plasma Version: 5.16.4 KDE Frameworks Version: 5.61.0 Qt Version: 5.13.0 ADDITIONAL INFORMATION To quickly reproduce this: PUI is available in the Tumbleweed repositories. Confirmed this behaviour on KDE Neon User Edition 20190829-1117.
Just to put this into context why this was filed against Plasmashell: package-update-indicator creates a status notifier using libappindicator and works fine with other SNI implementations (e.g. on XFCE). I also cannot reproduce the problem with the slightly older Plasmashell 5.14/Plasma Frameworks 5.54 in Debian Buster.
Possibly already fixed by the fix for Bug 399234. If you have the ability to compile Plasma from source, could you do that and give it a try? If not, KDE Neon Unstable edition will allow you to test as well.
I had problems compiling PUI on Neon unstable. Tried opensuse Krypton (5.12.80-Build10.155) instead. The Plasma package has the version 5.16.80git.20190901T175935~408f3ebbe-ku.85.1. There the bug is indeed not present.
Yay! *** This bug has been marked as a duplicate of bug 399234 ***