Browser Development • GTK file picker selection with keyboard or double click is broken

Since I updated to Pale Moon 34.3.1 the GTK(3) file picker is usable only by using the mouse cursor to press buttons. Keyboard actions and double-clicking produce no effects. I gave it a spin for a few days in case it was a misconfiguration on my end, but all other GTK applications I have work just fine as they always use to, only Pale Moon is unable to select files through keyboard or double-clicks.

I suspect this commit is the culprit, but I'm not 100% sure as there doesn't seem to be any immediately visible issue with it. If I switch to the native file picker by toggling the widget.allow-gtk-native-file-chooser preference everything works as expected, but I'd rather use the default value.