bug#51247: 28.0.60; Insufficient documentation of tab-bar.el internal functions

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: 51247@debbugs.gnu.org
> Date: Mon, 18 Oct 2021 20:21:48 +0300
> 
> >> It will display tabs or buttons from these menu items.
> >
> > When will it be tabs and when will it be buttons?
> 
> Tabs are buttons that switch window configurations.

But how do I explain in the doc string to the future programmers what
they should do to get tabs and what they should do to get buttons that
drop a menu?  Presumably, each of these needs a list of menu items of
different forms, but how should they be different?  How does the tab
bar know what to display given the menu items returned by these
functions?