The concept of primary toolbars no longer makes sense for GNOME3 applications. We don't need to emphasize a role of a toolbar as it's not desirable to have multiple toolbars in the first place. 

However having it defined and not having the associated special style is an issue. The constant should be deprecated.

Traditional design with a menubar and toolbar(s) should still be possible in my opinion, and should not be deprecated. If it will no longer be possible to create a traditional design with GTK+ 4, then lots of applications will need to stay with GTK+ 3 (and lots of those applications are still using GTK+ 2 anyway).

The new designs have a bad usability in my opinion. I don't want that for my application (which has a quite big menu).

The primary toolbar style was one of the nice things added in GTK+ 3 for a traditional design.

> it's not desirable to have
> multiple toolbars in the first place.

[citation needed]
Two toolbars work perfectly well in LaTeXila (a LaTeX editor). Users can hide them independently if they don't require them. I've never had a bug report saying that two toolbars are bad.

You can add as many toolbars and menubars as you want. I don't think the distinction between primary and non-primary toolbars has any relevance for that.

Yes, but for a traditional design, the primary toolbar style looked nice.

From my POV it's not worth the maintenance burden of added complexity. If you want to maintain it for it "looked nice", I'm afraid you'd need to do it per-app.

Sèbastien, I was thinking myself too about adding something to the theme for those, but after some use I really think it was just visual noise adding nothing to usability, also apps using primary toolbars w/o the old styling look more integrated with the current platform look, so we won't add back any special style for those, sorry, closing won't fix.