Frédéric, note that the 'owner' keyword means that the user running the program must also own the file; with most files in /usr/ being owned by root, this addition would only work if you're running Firefox as root.
Frédéric, note that the 'owner' keyword means that the user running the program must also own the file; with most files in /usr/ being owned by root, this addition would only work if you're running Firefox as root.