When you have Twitter Container and Amazon Container both installed, Firefox will open X/Twitter in the Amazon container, despite instructing it specifically to open it in the Twitter container.

I don't know exactly which container to blame but I'm mentioning it here.
For that functionality to work, I now have to remove this addon.

When I had this installed, it caused problems with tabs. If I logged into Twitter, logged out and then went to Facebook, 2 Facebook tabs would pop up. Same thing going the other way. Uninstalling the extension fixed things.

It log out every time you close firefox

very bad, it log out