Filesystem permissions

For many apps it is not an issue and provides additional security but in other cases it's very annoying and not trivial to fix.

Example1: opening a .docx from Thunderbird flatpak with OnlyOffice flatpak does not work out of the box.

Example2: mpv and VLC flatpaks work well for local files, but fail to open network shares from Dolphin.

I think a possible solution would be runtime permission dialogs when denied access.