UPDATE 7/12/21:

Since my last update a year ago, pretty much all problems of which I was aware have been fixed.

But since the last update (or maybe the one before that--but recently, in any case), a new one has cropped up:

When coming back to a Firefox session from Windows Sleep mode, TST has unloaded, and the main toolbar icon is gone. I've also seen this happen after a Firefox restart or crash. Going into the View menu to re-enable TST doesn't work, as it's also gone from there.

I've noticed at least one recent review that reports this problem when "starting Firefox."

The only work-around I've found is to open the Add-ons and Themes page, disable TST, re-enable TST, then go to the View menu to re-load TST in the sidebar.

It's a recoverable problem, but it's a pain to have to do this every day (and some times two or three times a day).

UPDATE 7-21-20:

Since the last Firefox update (to 78.0.2 64-bit), almost every time I left-click on a tab in the sidebar, instead of just selecting the tab, TST executes the "Move tab to new window" action. If the tab has children, the entire tree is moved to a new window. (I say "almost every time" as there may be one time in about ten that TST does not do this).

Needless to say, this is extremely annoying, as I then have to move my tabs (one at a time) from the new window back into the original window.

If I remember to do so, I can select tabs normally from the top tab bar, but muscle memory is ingrained for TST's sidebar, at this point, so I frequently forget to do that.

I don't know if this problem is due to a change in Firefox or in TST, as I'm clear on how their latest updates might be interacting. I can say that TST v3.5.13 did NOT fix the problem.

UPDATE 12-31-19:

The parent/child tab separation happens rarely now (and it's been a few months since I've seen it happen, so that bug may have been squashed.

ORIGINAL REVIEW:

Works pretty well, but sometimes child tabs get separated from the parent tab and other child tabs, with non-associated tabs in between. I've not seen a pattern to when this happens, unfortunately. At least the tabs are lost, but it can get confusing.

There is only one thing I find annoying about this extension: it automatically creates child-parent relationship between tabs which are opened from previous tabs. I'd rather have full control over tab-grouping (group them myself) than having the extension group tabs in a way I can´t even control from the options section.
Other than that, this add-on is the main reason I stick to FF, keep up the great updates!

Estoy empezando a utilizar este navegador y me ha gustado. .
De momento 4 ⭐

This new web extension is really disappointing and lacks the features of the original add-on.
I can't have both bookmarks tab open AND tree style tab open at the same time, which is a big letdown for me.
I can't close "all child tabs" at once anymore by clicking on the right click menu.
Can't close multiple tabs at once with a simple middle click on it as it always asks if I want to close multiple tabs before, which previously didn't for middle button.
When I close a tab, it tries to get the focus to the one under it (hence loading it), instead of the parent tab, and only half loads them (so that they remain buggy forever, until reload)
Also it doesn't work well with SNAP Links Plus, which, for some reason, creates useless temporary tabs with some weird indentation.
A lot of options disappeared from the add-on as well which makes it look like a watered-down rip-off of what it used to be.

EDIT :
The behavior of this add-on changed for the worst in the latest patch.
It now auto expands ALL the children and ALL their descendants upon tab selection (and not just those that were expanded before, like in previous versions)

There's no way to revert to the previous behavior and it's really annoying to have those huge FULLY expanded threes I didn't ask for.

This works pretty well. They way the hierarchies work is great. My only complaint is that the hierarchy structure gets lost when I close and reopen the browser. I have found a session manager that handles this so I wish it could just be added into Tree Style Tab.

Tree Style Tabs is definitely the best way to handle having a lot of tabs open at the same time.

Hi, dear Pino!

Thank you for your TST. It's very nice and useful/
Unfortunately, I've troubles with Ubuntu FF57: top tab bar doesn't hide. Right side addon's width doesn't change and close tab mark is in left corner, not in right as in previous versions.

Please, fix the bugs.

リリースから結構経ってだいぶ良くなっててうれしい
以下気になっているところ
1. "新しいタブでリンクを開く"アドオンと､"Glitter Drag"アドオンを使っていて､新しいタブを開いた時､1つ下の階層の末尾に子タブが追加されてくれない
1つ下の階層の1番上に追加されてしまう
TreeTabsではちゃんと末尾に追加されるので､多分TreeStyleTabのほうに原因があると思う

2. Ctrl+Tで新しいタブを作る時､今開いているタブの子タブとして開けない
全てのタブの一番下に開かれてしまう

3. セカンドサーチで検索した時､今開いているタブの子タブとして開けない
タブ構造の最末尾に開かれてしまう
要するに俺は全ての結果を今開いているタブの新しい子タブとして開きたい
TreeStyleTabの性格的に筋違いではないと思うしできるようにして欲しい

4. タブが太い
56までの細さのほうが好きです
タブの太さを調節できるようにして欲しい

Very useful. However too few options. I wish there's a way to one-click sort and group all tabs under same URL.

Found it pretty good but why does it force-enable tab containers? This adds another item to the context menu with no option to disable.

Can't live without it. One thing that annoys me is that the trees will sometimes randomly collapse by themselves. I've tried changing some settings but it still does it. cheers!

Very nice, but can't see bookmarks in vertical also. See to Vivaldy layout, two vertical spaces, one for tabs and the other for the bookmarks. If only I could have a shortcut to switch from one to another, at least the lack of seeing both columns at the same time would have less impact.

For years now, trees are easily malfunctioning: many kinds of positional/branch errors or even sticking to a place for no reason.
There should be option for no animation after reordering was requested.
No "unload tree" button exists, not sure if possible.
During last month, a couple of tabs got not clickable, requiring use of keyboard to navigate/close.

VERY Useful! I just wish we could change the look and feel of the sidebar, have thumbnails, and have it Support (as in group them accordingly to...) Mozilla's Multi-Account-Containers. (See https://github.com/mozilla/multi-account-containers/#readme )

Suggest: if it's not possible to auto-hide the TreeStyleTab-Sidebar, would be great showing the tree in a new window, like the Bookmarks Manager window.

Hey!
Can you implement API that allow other extension to integrate into TST? Details https://cup.aihedy.com/ru/firefox/addon/reloadmatic/reviews/996192/