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: Wed, 20 Oct 2021 19:50:53 +0300
> 
> The tab bar is created from the list where elements are either a string,
> or a menu-item with a title and a binding.  The title is displayed as
> a button on the tab bar.  Clicking on such button calls the binding.
> The binding usually is a command that switches tabs.  But the binding
> can do everything.

Thanks.  What if the function in tab-bar-format returns nil -- how is
that handled?