Literally the reason I use Firefox over Chromium browsers.

Чудове розширення. Забрав зверху панель вкладок)

Bestes Addon! Sehr praktisch! Ich empfehle auch die anderen Addons die Tree Style Tab erweitern anzuschauen.

Takes up too much screen space, when not working with browser window maximized. Please add a feature to auto-collapse to the left or right when not in use and auto-expand the toolbar while hovering over it only.

Thanks for all the features included so far. Cheers!

私にとって最早不可欠な拡張です。

Like it.
Gives me the freedom to use those extra couple of cm's at the top of the screen, by utilising the side of the screen a bit.
Been using it now several years.