At the least, you could imagine having a shared session for all the tabs in a same window. But a new incognito window should be clear of any history.
This is really annoying when you always use your web browser in private mode, but don't close it regularly. It means that e.g. youtube already builds a profile about me from my previous searches even though I'm not logged in. If I were that concerned I would close Firefox, but the usability issue is just too big for me. Having the best of both worls would be awesome.
Not in firefox, or, at least not for me.
And yes, you're right if I log in on either one of two private windows then the other one is also logged in. That's actually a bug in FF afaic.
And in a VPN and I think you get at least some chance at some privacy. Hopefully.
Even Internet Explorer has File > New Session.
Meanwhile, my personal container won't log me with my gmail/work account when I watch cat videos on youtube.
If I used facebook, I'd have a facebook-specific container. Just open a tab in it, and I'm logged in, but no cross-container tracking.
Also, history is retained, and all in one big pool (unlike having actual separate profiles).