SUMMARY
Most of the spin boxes in MuseScore Studio will not accept keyboard input when run within a Plasma Wayland session. Xorg sessions work fine. This includes setting the initial number of measures when creating a new score, and all of the spin boxes under "Appearance" settings for any element. Only mouse interaction with the up and down spinner buttons can change the values. The only spin boxes that seem to accept keyboard input are those in options found in the menu, such as "Preferences", "Style", "Page Settings".

This bug does not happen in GNOME Wayland, and appears to be an issue with how Plasma's xwayland sends/blocks keyboard events.

I am experiencing this bug using the latest official MuseScore Studio AppImage (4.6.3) and Flatpak (4.6.3) in Fedora 43 with Plasma 6.5.1.

STEPS TO REPRODUCE
1. Start MuseScore Studio.
2. Create a new score.
3. On the second page of the new score wizard where you can set initial number of measures, click on "32 measures, no pickup" and highlight "32" under "Initial number of measures".
4. Attempt to type in a new number of measures.

OBSERVED RESULT
Nothing happens. The backspace key can delete the selected number, but any numbers typed on the keyboard do not appear. This bug can also be reproduced by attempting to edit any of the appearance settings for a notation element (e.g., click a note or whatever, go to the "Properties" tab on the left side of the screen, then click "Appearance"). Unfortunately, this makes many fine positional adjustments impossible as the spinner buttons often only allow large jumps in position.

EXPECTED RESULT
It should be possible to type into the spinner boxes.

WORKAROUND
1. Go into System Settings, then select "Application Permissions" (under "Security & Privacy") → "Legacy X11 App Support".
2. Under "Listening for keystrokes", select "Always allowed". (The default is "As above, plus any key pressed...").

You will be warned that "...using this setting will reduce system security and permit malicious software to steal passwords and spy on the text that you type. Make sure you understand and accept this risk."

After changing this setting, all keyboard input works as expected in MuseScore Studio.

SOFTWARE/OS VERSIONS
Linux: Fedora Linux 43
KDE Plasma Version: 6.5.1
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0

ADDITIONAL INFORMATION
Relevent MuseScore bug report: https://github.com/musescore/MuseScore/issues/28866