When opening a application from the application menu (or Application Launcher/Dashboard) some apps will not show their window, if they are residing in the system tray (for example kgpg, kwalletmanager, ...) This is not what a normal user would expect. Instead the only way to show the kwallet manager window or kgpg is to go to the system tray and click on the respective icon there. There should be at least some visual feedback to hint at the user, that the apps are hiding there and that they did not crash at the srart time for example.
FYI, this isn't a function of plasmashell, but of the apps themselves. I'd suggest you file bugs/issues against these apps individually.
Thanks for info, but some kind of visual feedback would still be appreciated. We have bouncing icon for applications that are starting / loading cycle in the taskbar, so maybe there could be a popout above the systray if the application already resides there. Therefore I also listed it as wishlist.
This is really the application's task. If I have KMail minimized in System Tray and launch it again, it brings its window to the front. I also don't see an easy way to relate a newly launched instace of an application that doesn't open a window to an already existing tray icon.