SUMMARY Looking online, Kwin seems to ignore primary/secondary monitor rules when deciding which monitor to open a windows, and instead chooses which display to open a window in by which display is in focus via mouse. However, opening an application via the app menu through the meta key seems to ignore this rule, either because it switches focus to the other desktop (strange because it does not even have a panel) or some other type of focus rule in engaged when the meta key is pressed. Applications opened via keyboard shortcut or Krunner open as expected, however anything opened via application menu is sent to the "wrong" monitor STEPS TO REPRODUCE 1. With two monitors connected in extend mode, move mouse into monitor where the panel lives 2. Open the application menu, either via mouse or with the meta key 3. Open any application OBSERVED RESULT Application window is sent to the monitor that is not in focus EXPECTED RESULT Application is opened on the desktop that was in focus when the application menu was opened, either via mouse or meta key. SOFTWARE/OS VERSIONS Windows: macOS: Linux/KDE Plasma: Fedora 30 (available in About System) KDE Plasma Version: 5.15.5 KDE Frameworks Version: 5.58.0 Qt Version: 5.12.1 ADDITIONAL INFORMATION
just to clarify, this behavior occurs regardless of whether the application menu is opened with meta or a mouse click
> seems to ignore primary/secondary monitor rules when deciding Yes, that's correct. If you don't like this behavior, "Active screen follows mouse" option may be very helpful (it's located under Window management, Window behavior).