[kwlug-disc] Firefox tab addons - tab folders?

[unsolicited]

Khalid, recently, indicated he has something like 240 tabs open in 
Firefox.

I've had to go to taberwocky as firefox version updates have left 
whatever addon I was using in the dust.

I now have three rows across the top of opened tabs. (I like tabs 
across the top, not the side.)

This is getting irritating. Yes, I could close the tabs. Don't want 
to. tthhpptt.

Any add ons out there that keep tabs along the top, but let me put 
them in folders? i.e. There are groups of tabs related to whatever I 
was investigating at the time, but haven't gotten around to a 
conclusion on yet. It would be nice to group these tabs into a single 
tab bar entry that was expandable.

Suggestions?

(Note, I'm not talking bookmarks, here. Opened tabs.)