bug#51648: 28.0.60; `tab-bar-close-button' and `tab-bar-new-button' should be documented in the manual

[Eli Zaretskii]

> From: Juri Linkov <juri@linkov.net>
> Cc: luangruo@yahoo.com,  51648@debbugs.gnu.org
> Date: Sun, 07 Nov 2021 20:31:34 +0200
> 
> >>   (setq tab-bar-close-button (propertize " x" 'display (propertize "✕" 
> >> 'face 'tab-bar-tab-inactive) 'close-tab t))
> >>   (setq tab-bar-new-button (propertize " + " 'display (propertize "➕" 
> >> 'face 'tab-bar-tab)))
> >
> > I thought there were some defcustom's for that, but they weren't
> > easily discoverable by browsing the tab-bar customization group.  But
> > if you didn't intend to let users customize those, it's up to you.
> 
> The problem is that I don't know how it's possible to customize
> a string with text properties on it.

Well, the request was to allow customization of the image on the tabs,
so maybe have just the image(s) customizable?