Firefox v137 broke vertical tabs

[SEGFAULT3102]

Bug description:
Horizontal tabs are no longer hidden after updating

Steps to reproduce:

• upgrade firefox to v137 or higher, or boot firefox with auto updates as of april 1st 2025

[MortezaFp]

+1

[meatcar]

Following these instructions turns on the native vertical tabs: https://support.mozilla.org/en-US/kb/use-sidebar-access-tools-and-vertical-tabs If you're using sideberry, clicking the SideBerry icon gets you back your original UI.

It's not perfect, the userchrome collapsible sidebar toggle stops working, but otherwise useable.

[SEGFAULT3102]

My solution was to remain on firefox v136.0.4. The new implementation is not up to par with the legacy implementation, imo.

[D3SOX]

Not a great solution. I would highly advise you to not run old versions of software just because you like the looks better (especially browsers!) :)

Btw my solution was to create my own theme with the features that are essential to me, based on well-known maintained Firefox CSS-Tweak repos. That way the code is much more minimal and easier to customize. You can find it at https://github.com/D3SOX/firefox-minimal-compact-css/