Very nice extension. I added 'Multi Account Container' and Pinned it there so it always opens up, runs in the background and is out of my way as a tiny tab in the corner.

Exactly what I needed

Its surprisingly ingenious.

I love this plug-in! Absolutely wonderful. I also leave one pinned tab with Gmail settings and then use Gmail in an unpinned tab. Thank you Evan for your great work

The addon functions perfectly and does its job without any hassle! I like to open the account page in one window, then just minimize it and open a new window to continue using Firefox