Braille 6-key input non-functional on Linux

Issue type

Accessibility issue (e.g. for keyboard-only or screen reader users)

Bug description

The new 6-key braille input works great for me on Windows, but doesn't work at all on my two Linux systems.

Steps to reproduce

1. Select a rest
2. Tab to braille panel (enabled first in Edit / Preferences / Braille if not already)
3. Press "N" to enable braille note input
4. press and hold FJKL to enter a quarter note C (dots 1456)

Result: nothing happens

On my Windows machine, a note input cursor appears after step 3, giving visual feedback that note input is active. This does not happen on Linux.

Screenshots/Screen recordings

No response

MuseScore Version

OS: Debian GNU/Linux 11 (bullseye), Arch.: x86_64, MuseScore version (64-bit): 4.3.0-233310304, revision: github-musescore-musescore-53f2905

Regression

No.

Operating system

Debian 11

Additional context

If I run from the terminal with the "-d" option to show debug info on the console. I see that nothing is even trying to happen. At step 2, I see "ActionsDispatcher::dispatch | try call action: nav-next-panel" followed by "UiActionsRegister::updateEnabledAll | currentCtx: UiCtxNotationOpened". But, no output to console at steps 3 or 4.

I took a brief look at the source to see where thing could be going wrong, but the best I can do is see that it doesn't appear to be reaching the point in the code that processes keyboard input with the braille panel.

Note: both my Linux systems are Chromebooks (different models with different keyboards) which could possibly be relevant, but if so, that would be surprising, as I don't run into Chromebook-specific issues very often at all. If "N" worked but multi-key input did not, I might wonder, but since not even "N" works here, it seems the problem must be more basic.