X11: Can't add effects to Audio Bus, selection impossible in popup

[akien-mga]

Godot version:
44e89cb

OS/device including version:
Mageia 8 x64, Plasma 5 on X11 with KWin

Issue description:
In the current master branch, I can't select audio effects to add to an audio bus in the popup menu with the mouse:

I can however select items with the arrow keys and Return.

Possibly a regression from #41640 (CC @EricEzaM), otherwise might be a general X11 window issue (CC @pouleyKetchoupp).

Steps to reproduce:

• Open project on X11
• Select Audio bottom panel
• Click "Add Effect"
• Try to select an effect

Minimal reproduction project:
n/a

[akien-mga]

This is fixed by #41689, so indeed a regression from #41640.

[EricEzaM]

Awesome, already solved before I get to look at the ticket :P