I'm trying to force myself to be able to manage my Firefox tabs better and not just let open tabs pile up over time, and I was interested in the auto-close feature. It would probably be a good idea to have tabs I don't come back around to within a certain period of time auto-close. However, I would also like if some number of tabs could stay open permanenetly without auto-closing. Is there anything specific that can be done to achieve that? Would having tabs auto-close but putting tabs I want permanently open in a tab collection/group work, for example? Or is there no way to achieve this currently?