bug#15748: 24.3.50; `customize-group': Provide a way to hide/show all values

[Eli Zaretskii]

> From: Lars Ingebrigtsen <larsi@gnus.org>
> Cc: hmelman@gmail.com,  15748@debbugs.gnu.org
> Date: Thu, 12 May 2022 02:28:24 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > It now works in "*Customize Group*" buffers I tried, but the problem
> > is still there in some other similar cases.  For example, try
> >
> >   M-x customize-apropos RET window RET
> >
> > In the resulting buffer, the second 'H' still gets the same Invalid
> > widget error.  The same happens in a buffer created by
> > customize-faces.
> 
> I was apparently calling the wrong interface function; now adjusted.

Thanks.

For some reason, 'H' to expand the settings is much slower than 'H' to
hide the expansions, even in buffers that are not very large.  Not
sure we care about this.