This is A must have plugin for every one, it's more piratical to put the tabs on the side and use the screen real estate to display more content. And for any one which to work with many tabs to have a clue for which tab came from which page and how the tab's are related.

Thanks you @Piro for this great and essential extension. I did worry from the transition to WebExt that this extension will vanish, and start looking on Vivaldi browser which have similar option but a more limited options compared to this extension.

Looking forward for Mozilla to extend the API to allow more control on the browser.

Thanks again.

Thanks Piro for making it work with 57!
One small thing: the about:preferences icon in dark theme is invisible (shows fine in regular tabs).
Also, it would be *great* if there were an option to select tab on mouse hover.

With the speed of Firefox 57+ and the super tree style tabs experience via this addon, there's no browser that can compare. Thanks Piro!!!

Just upgraded to ff 57, every thing is working great except:
1) ff tab bar not hidden
2) when collapsing a tree it overlaps with the tabs and trees above it. I have to keep all the trees expanded now when using the Metal theme!
---
So for those having the same problem with the metal theme, adding this fixes it:
.tab.collapsed {
margin-top: -24px;
}
.tab {
height: 24px
}

Working in 58, but after I restart, all nesting is gone...

"by Piro (piro_or) (Developer) on September 26, 2017 · permalink
Due to unavoidable reasons, TST 2.0 is strongly depends on new WebExtensions APIs introduced at Fx57, so it can't become compatible to older versions of Firefox. Please keep using TST 0.19.x for a while, until Fx57 is released."

Nope. A few days ago the tree structure stopped working in my Firefox 55, with TST version 0.19.2017090601. Now I just have a vertical column of tabs. The whole point of using TST is to be able to arrange tabs into trees, right? Like others are commenting here, TST is a "must have" extension for me. What's up?

Essential

Supporting for FF57+ is awesome!

BTW, does WebExtension has no API to hide native tab bar?

I tried other browsers, but without vertical/tree style tabs they were just unuseable for me. I can't understand why this isn't the default tab UI for all browsers implemented without any extension.

great but now i can't use it on newer firefoxes like 52+

Works great.

The one thing that bothered me enough (apart from hiding the top tabbar with the userChrome changes mentioned in another review) is the fact that the tabs are padded too much for my taste.

Luckily there's a "Extra style rules for sidebar" textarea in the options page, where you can put extra CSS rules for the sidebar. I've added the following in that textarea:
/* slimmer tabs in sidebar */
.tab {
padding: 1px;
}

嬉しい！

Until mozilla gets around to creating the API to hide the tab bar, do this:

Go into about:config and set browser.tabs.drawInTitlebar to false

Go into about:profiles, click Open Folder on root directory, create or open the "chrome" folder and create or edit a "userChrome.css" file in that folder (capitalization counts, even on Windows). Enter the below in the userChrome.css file, save it, close and restart Firefox:

/* Hide tab bar */
#TabsToolbar { visibility: collapse; }
#sidebar-header { display: none; }

absolutely elated that TST will be 57+ this is the only add-on I cannot live without and why I use Firefox exclusively. Thank YOU! Piro

It makes FF57 usable at least(but still missing much functionality). Is there any chance we'll be able to remove default tab bar after installing this addon? Is there webexternsion api to do this? Another thing is that I cannot find a way to move tabs to right instead of left side of the window...

以前のバージョンと比べると再起動したときに勝手にツリーが崩れていたりするバグが無くなっていたり、見易さが向上していたりでかなり使いやすくなった様に思います。
しかし、上部にあるFirefoxデフォルトの横型タブは以前のTreeStyleTabの様に消す（見えなくさせる）事は出来ないのでしょうか？
オプションを見てもそういう風な設定は無さそうです。Firefox側で制限されていたりするというのならば仕方ありませんが...

もう一つ、オプションでテーマを設定してもTreeStyleTab最上部のサイドバーを閉じるボタンがある部分の色が変わらないのは仕様でしょうか？Firefox側のテーマもTreeStyleTabのテーマと合わせて暗色系にしたのですが、そこだけ白くなっており、他の部分と比べ少し浮いているのが気になります。

edit: なるほど...わざわざbugzillaへのリンクも貼っていただき感謝します、そういうことなら仕方ないですね。Firefox側の対応に期待して首を長くして待つことにします。

it works on 57!

Great!

Been using TST for many years and was afraid I'd lose my favorite extension after Quantum v57 upgrade. Thank you Piro!

You sir, are a hero.

And those who want FF to look like it did with the previous version of Tree Style Tabs, see the hints here: https://news.ycombinator.com/item?id=15342728

I am really glad this extension now supports FF 57+. Now I can return using Firefox.

Can you add compatibility with 55?

Working with a lot of tabs is a huge pain - but now I am able to organize them and not loose track. Please keep the updates coming.