Best Tree Tabs extension ! And I've tried several !
This one groups the most features I need :
- Tree view
- Tabbed Groups (it would be nice to be able to select background colour of tab like in Opera)
- Pined tabs at top
- Themes (you can create your own one quite easily)

And more !
I also use this one with Opera ;)

Thanks for this great "must have" extension !

Looks nice, with several features. It might even have what I'm looking for, which is to save and update multiple windows tab sessions, but after more than one hour with it, I still don't know even if it has that (others were really intuitive without any learning curve whatsoever). And there is no instructions. Looking for another one, 4 stars because it is difficult to find an add on with the tree structure though, and I'd like the developer to continue working on it...

Sometimes the tree structure of sorted tabs gets lost, which is really annoyning. The backup feature does often recover this, though. I've tried a couple of similar add-ons, but I'm always coming back to Tree Tabs because of its many useful features. Hoping for a new, more stable version.

Of the minuses:
-No general tab search across all groups.
-Auto sort by template does not work
-Skinny setting hotkeys

Great and essential Add-on ... better than Tree Style Tabs. However, Automatic Tab Assignments has stopped working (even tried on a fresh Firefox install). This was a big help keeping tab-sprawl at bay, as now I have to manually keep moving my tabs around. I'll keep using it as long as it's mostly working, but I'm sad that development seems to have stalled.

After some months of treetabs missing in the sidebar, it has suddenly reappeared, with all 300+ tabs still in order!
I'm so happy about this uber helpful addon getting back on track!
My donation is meant as a big "Thank You!" as well as an incentive to keep on caring about this georgeous baby.

Great bu buggy...
the tabs all appear in the same group (loss of structure).
Plus various bugs monthn annoying.
And sometimes all the tabs disappear. This morning, I lost everything, it's not acceptable: I give up to find something more reliable.

Easily my favourite extension that allows side tabs, as it allows labelling and grouping of tabs into groups.

The problem I describe below the fold is easily fixed by the declopers' suggested workaround, and hopefully will be fixed soon.

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The extension constantly flashes the entire tab sidebar section white every 2 seconds or so - this only started happening today, but I'm not sure why.

Here's a gif of the behaviour - https://gph.is/g/4gpQ7WE