Extra mouse buttons do not function when used as shortcuts

[Violet-RM]

Pixelorama version:

1.0.1-stable, specifically the flatpak

OS/device including version:

Linux Mint 22

Issue description:

When setting my shortcuts to my liking, I want to set undo and redo to mouse4 and mouse5, called mouse thumb button 1 and 2 in the settings. To clarify, I am not trying to edit the default bindings, and I am able to set other shortcuts (ex: i set Ctrl-Alt-Shift-1 just to see if i was doing something wrong when setting shortcuts in the first place, and it worked as expected). I only encounter this issue when I am setting a binding to side mouse buttons.

Steps to reproduce:

1. Set a shortcut to a mouse thumb button
2. The shortcut is not executed when using the mouse thumb button and nothing happens

[Violet-RM]

Still an issue in the 1.0.3 release