If you are familiar with userChrome.css, you might try this, as it works for me:

/*  #######    */
@namespace html url("http://www.w3.org/1999/xhtml");

#toolbar-menubar {
  order: 1;             
}

unified-toolbar {
  order: 2;             
}

#tabs-toolbar {
  order: 3;              
}

If not, I'll add more instructions:

Okay. I probably should have done initially, but I was in a hurry: here goes - click settings>general and scrollodown to config editor - search for toolkit.legacyUserProfileCustomizations.stylesheets and change to true - then you need the chrome folder in profile, and a userChrome.css file. - exit and restart TB and it should work, although I've sometimes found I have to restart TB twice to see changes in userChrome.css

Thanks! I hope this makes it into the main branch as this was an unfortunate oversight.

I spoke too soon. I open TB and it opens as expected. I exit and open it again, and the mail page is empty. I add or remove a blank like to the CSS file and open TB again, and it opens. This fix, unfortunately, is very inconsistent. Any ideas?

Umm, I reverted the changes and the issue with an empty mail page is still there. This might be a larger issue with TB.

The empty mail page sounds like a new issue, not related to the CSS file (?)

The empty mail page sounds like a new issue, not related to the CSS file (?)

I believe this is true.

I would also vote to return the menu bar to its original location. It seems more standard in Windows apps to have the menu bar above any toolbars. This immediately stood out as unusual to me upon loading v115. I'd like to see this change reverted or made into a setting for those who particularly want the menu bar to be below the toolbar, as that seems less typical.

Just been upgraded to Supernova and wishing I hadn't. The toolbar location is really annoying. Disappointed to see no progress on this thread 3 months later. Wondering if I can revert to the latest version of 102.

Yes, you can possibly revert to 102, but the process is problem-prone, so I suggest doing a backup first. Try:

   Exit Thunderbird if running.
   click windows key and 'r' key
   Enter: thunderbird.exe -P --allow-downgrade
   click on 'OK' 

Regarding the toolbar location, my guess (and that's all it is) is that TB hid the menu bar back in release 78 and, when introducing the new toolbar, assumed people were no longer using the menu bar. But they were wrong in that decision. There is a clone called betterbird that kept the toolbar under menu bar and defaults to unthreaded . That's an option if you don't care for the new direction.

Thanks, That's all very helpful.

Its not just being over the menu bar that is weird and different. I think we could choose where to put it in the old days and I certainly always had it under the folder tabs so it was the first thing next to your actual messages. As the toolbar buttons are the tools you access most when reviewing your messages it seems most intuitive to have them closest. I know in time I will get used to the new position and shape etc but in the meantime I keep trying to change folders when I go to the old delete button location. Very irritating.

David,

Would your initial answer also work to put the unified-toolbar in order 3 below #tabs-toolbar in order 2 if one swapped those 2 commands over and edited the numbers accordingly.

I have looked up some other threads about creating a userChrome.css file and hope I have the general idea. I am not sure about the following code from your answer

/* ####### */

My guess is this is just a message header and not a program line. Am I right. Do I need to substitute anything for #######

Anything in between the /* and the */ is just a comment. I like to use them as I forget sometimes and the #### helps in delineating different sets. So, the line is meaningless and can be left or deleted.