[batiudrami]

I mean there are plenty of things wrong with it. It’s a workaround, so:

* if you use this, you can’t use any other sidebar at the same time

* you need to put in custom userchrome.css to hide top tabs. Once you’ve done this you can’t easily swap between vertical and horizontal tabs.

* it’s ugly and, while not exactly buggy, there is a lot of UI weirdness that comes with it being a workaround

I still use it and have done for years but native support would be a big improvement.

[nine_k]

TST is not ugly at all, but definitively is an exquisite hack. This fact limits its capabilities and sometimes even its usability.

OTOH, Tree Style Tab is the best thing that happened to the Firefox UI in last few years.