Wonderful that this extension is back!
I request for a quick tab search similar to how other sidebar tab extensions are now providing. That will make this a perfect extension.
Also if you could have hiding the close button as an option somewhere that will be nice.

must have

only reason why i am using firefox

Seems to work great and doesnt ask for ridiculous permissions. I appreciate that.

One request i have though. Could it be made into a popout like tabsoutlier on chrome?

I really needed a proper tree-style extension after Tab Tree died, however I can't view any tabs. Something to do with the way it is themed no doubt. I am on 66.0.2

I had to change the theme to dark, and everything else is great! The wiki is very detailed and makes this a great tool in conjunction with tridactyl.

この拡張機能があるから Firefox を使っていると言っても過言ではないです。

Quantum になってアーキテクチャが変わったことも起因していると思いますが、ブラウザ起動後にツリー型タブとなるまで数秒掛かるのが少々気になるものの、機能的には満足しています。

THIS IS AN AMAZING ADDON! and its made by an amazing author, no big bugs exist, only small ones, and even they get patched almost immediately by the author, do yourself a favor, and get this extension, with just a little setup, your firefox will be 100 times better than it already is., pair it wih the tab hider extension for the ultimate pairing!

Tips for using this buggy addon:
0. Deal with it.
Ok, 1. Organize with folders or folder trees instead of tab trees when you're working with a big chunk of tabs for maximum safety. Never ever should you make blank tabs (about:blank, new tabs, or blank pages) father of other tabs. Definitely gonna f up your tree after a restart if you spot buggy behaviors with tabs before it. This one is on Firefox.
2. You may often encounter scrambled up tree structures and missing tabs that are actually hidden after a restart, so you might want to have "expand all trees" in your context menu to make them reappear, or enable expanding trees with double click. This alternative doesn't always work though.
3. Use a session restore addon that saves and restores tab metadata 'by nature', just in case everything is beyond redemption. You might already be using one anyway so this tip goes the last.