Disclosure: I'm the author of the add-on mentioned in the story. We tried a few different UXs and none of them felt ideal. We have an open issue to add Messeng

Disclosure: I'm the author of the add-on mentioned in the story. We tried a few different UXs and none of them felt ideal. We have an open issue to add Messenger to the list of FB domains that are contained. https://github.com/mozilla/contain-facebook/issues/45 https://github.com/mozilla/contain-facebook/issues/45