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: Po Lu <luangruo@yahoo.com>,  51648@debbugs.gnu.org
> Date: Sun, 07 Nov 2021 19:37:22 +0200
> 
> >> > What should be possible is to find the customization by browsing the
> >> > tab-bar Custom group.  If that is not currently possible (I didn't
> >> > check), then we should probably do something to fix that.
> >>
> >> It isn't, FWIW.  Thanks.
> >
> > Juri, can we please fix this?  Thanks.
> 
> Please specify to what extent it should be customizable.
> 
> Currently configuration of these buttons is possible with e.g.
> 
>   (setq tab-bar-close-button
>         (propertize " x"
>                     'display
>                     `(image :type svg
>                             :file "checkbox-mixed.svg"
>                             :margin ,tab-bar-button-margin
>                             :ascent center)
>                     'close-tab t
>                     :help "Click to close tab"))
> 
>   (setq tab-bar-new-button
>         (propertize " + "
>                     'display
>                     `(image :type svg
>                             :file "checked.svg"
>                             :margin ,tab-bar-button-margin
>                             :ascent center)
>                     :help "Click to add tab"))
> 
> that uses SVG images.  Also it's possible to use Unicode chars with
> 
>   (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.