Re: Faces customization group linked from mode groups

[Juri Linkov <juri@jurta.org>]

>     Is not this the opposite way of the way Richard suggested? But the
>     problem you mention should essentially be the same, or?
>
> The possible problem is that a custom buffer for
> font-lock-highlighting-faces would include lots of parent groups.
> I agree it would be nicer to add a one-way link.

To my surprise the suitable link type is already implemented but not
documented.  The name of such one-way link type is `custom-group-link'.

After adding it for example to the `cpp' group like:

(defgroup cpp nil
  "Highlight or hide text according to cpp conditionals."
  :group 'c
  :link '(custom-group-link :tag "Font Lock Highlighting Faces group"
			    font-lock-highlighting-faces)
  :prefix "cpp-")

it displays in the customization buffer an additional line:

   See also [Font Lock Highlighting Faces group].

with the button that creates a new customization buffer with the
`font-lock-highlighting-faces' group.

The cost is adding this link is losing another link in the same buffer
which looks like:

   Parent documentation: [Manual].

It seems the logic of Customize assumes that if the group has a link
explicitly specified in `defgroup', then adding another default link
to the parent manual is not necessary.  I don't think this logic is valid
for `custom-group-link' link type.

-- 
Juri Linkov
http://www.jurta.org/emacs/