Weird address/title bar behaviour on Mozilla Firefox Developer Edition

Nothing really jumps out at me from the already known bugs — do you see the same if you restart into Troubleshoot Mode (from Help menu)?

I'm having the same issue - I have about 30 windows open usually (Firefox DE 156.0b2, macOS 26.6.1)

Only one window, plus new windows I create, has an address bar and toolbar - the others do not, and I can't see how to get them back (I've beta tested since Firefox 0.1 and Thunderbird before that, this is the first time I have had a bug this major)

Also I cannot scroll in the windows without address bars, so essentially the entire UI has disappeared except for the tab bar

I tried turning off extensions that I thought would interfere, but that didn't make a difference...

I'll basically have to work out of one window for a bit, breaking my organisation of titled windows and tab groups (Window Titler is also broken due to a change in how windows are titled with domain first, but that's a separate issue)

UI behaviour is identical in Troubleshooting mode (address bar only in 2 windows, one previous, plus what I created after updating, windows without address bars cannot scroll) (DE 156.0b2, macOS 26.6.1)

Ah okay, it has a regressor now, there was a partial backout between b1 › b2 › b3: bugzilla.mozilla.org/2068779 + bugzilla.mozilla.org/2068798

Beta 3 starts building in about two hours, and will start rolling out hopefully later today for you to check for updates.

Tested 156.0b3 just now and it seems to have been fixed, both vertical tab bar resize, address and titlebar now work properly. Thx for the support, quick response and to ab20 for providing more info while I was afk.