Unfortunately, there is no solution. :-( However, there is a request to add such an option to Firefox. (Option to disable the notification bar). See here: https://bugzilla.mozilla.org/show_bug.cgi?id=942461 There was even someone who wanted to implement it, but he was thwarted by fussy admins. Maybe they need some more hints that this is a real issue (#1 question at the moment) So please go there, sign up, and vote for that issue. The more people do so, the more likely it is that this will be implemented. (The vote button is a bit hard to find on that page. Just Ctrl+F and search for "vote")