Doesn't work at all.

Signed into Facebook and addon did nothing, it just told me to sign in with no option to do so within itself.

It would be nice to make it react faster and fix bug with not logging in if you are not logged in messenger directly... nonetheless brilliant idea

Works as expected. Had an error at the begining coming from Facebook but is gone now. When used on the side bar, a chat doesnt cover the entire side bar but exceeds it a bit, whereas on opera a chat takes the entire side bar without having to scroll to see it.

There are no notifications when a new message is received and the window itself is so small and shrunk down that it makes clicking/using certain features like "reactions" impossible because they're out of view when you try to mouse-over. It's more effective to go to messenger.com.

It is somewhat amazing how ignorant people can be when giving a one-star review. Yes, the user experience is not as good as it used to be before the recent FIREFOX UPDATES, but it still does the job.

Top Tool! THX!