KDE installed → Application launcher key → file:///usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/Kickoff.qml:157:34: Type FullRepresentation unavailable file:///usr/share/plasma/plasmoids/org.kde.plasma.kickoff/contents/ui/FullRepresentation.qml:43:5: KickoffButton is not a type
Asking your question there was wildly off-topic. The correct path is to open a new thread instead. I’ll move you post, please take the time to ask yourself or ask someone what’s the best way to proceed next time, that will increase you chances of getting a useful answer, and increase the quality of the forum
Edit: I made a mistake, my apologies are in the other thread.
I have also installed KDE and faced the same issue. I don’t know how to edit the application launcher but there might be two workarounds:
run qubes-app-menu from alt-F2. this one runs the identical app menu that was on xfce.
or just right click on the application launcher (the button on the bottom left corner) and select show alternatives. The “application launcher” is failing but the “application menu” alternative works.