Comment # 3 on bug 1224940 from Bruno Pitrus

1.Do you have xdg-desktop-portal-kde installed? It is needed for proper support
of file dialogs in Gtk-based apps in KDE.

2. Please run `electron
https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/file` and try
to trigger the file input dialog from that page. (I'm trying to isolate whether
this is a Signal problem vs Electron problem)