[thomastjeffery]

I've been using TreeStyle tabs for a few months now.

While I love the tool, it definitely has some rough edges with integration.

It has the same problem Firefox Multi-Account Containers has: Trying to change internal UI for an internal feature by using an addon simply isn't practical (yet).

[kevin_thibedeau]

It was practical before they killed XUL extensions and went with a crippled Chrome clone that can't hide it's horizontal tab bar. It's time for Mozilla to embrace and extend that garbage.

[kissickas]

Read shridharama's comment here for the fix:

https://github.com/piroor/treestyletab/issues/1525

[konart]

It's in the works for some time now: https://bugzilla.mozilla.org/show_bug.cgi?id=1410548