Ohodnoceno 3 z 5 hvězdiček

You say
" This add-on will become obsolete with the new Thunderbird UI "Supernova" that will be released with Thunderbird 115 in summer 2023, as that new design already moves the tabbar above the toolbar, in addition to introducing space-sensitive toolbar buttons. "
I don't understand
I want that :
Menu bar
then
tollbar
then
Tabbar
Thunderbird 115 doesn't do that.

Thunderbird 115 does move the toolbar over the tabbar. You should have the Toolbar on top (with window features: close, minimize, etc.), followed by the menu bar (hidden by default) and the tab bar (hidden unless there are two or more tabs).

The position of the menu bar has never been influenced by this add-on. All it did was move the toolbar up (hence the name), and in 115 the toolbar is already at the very top.

I personally am not sure if moving the menu bar down was a good choice, but I'm giving the new design a chance first. If there are indeed use cases that truly benefit from reverting the change, I'm sure there will either be a core option or an add-on doing so at some point in the not-too-far future.

If you already decided that you can't live with the change, see https://support.mozilla.org/en-US/questions/1422908 for a css hack.

(Sorry for messing up the add-on description, of course the new design moves the *toolbar* above the *tabbar*, not vice-versa. I corrected the description now.)

Ohodnoceno 5 z 5 hvězdiček

Very good.
Please, Update to Thunderbird 115*
I would pay 5$ for