I use this a lot, really. Mostly when "bookmarks" are in the side-pane.
I started structuring the bookmarks in folders, and 2Pane just lets me visualise the CONTENT of such folder when only clicking the folder name.
I am a bit worried though, as (newer versions of) FireFox starts labeling this extension as "outdated" (or obsolete?)
warning that in the foreseeable future fireFox will "change the way plugins work"
Will this one be re-written ?
Maybe that's a lot of work ( IANA programmer ) , and maybe it would help to start a kind of fundraiser.
Yes everybody frowns over "paying for something" , but if I'd know how the developer would be needing to "update this to the new structure", I think it'd be worth to have it updated (instead of needing a crash course in FireFox development, analyse what this really does, get a few pals together to organise a re-write : I'm not even sure I have pals who would do it, or who could, let alone do this by myself.
that worry aside (it might just stop working?)
This really IS a good thing to have. Only realised it's real potential quite late, but it is there.