Re: Faces customization group linked from mode groups

[Juri Linkov]

>     The cost is adding this link is losing another link in the same buffer
>     which looks like:
>
>        Parent documentation: [Manual].
>
> I don't understand what such a link would mean.
> What is "parent documentation"?  What is "Manual" the name of?

It is a link in the parent group pointing to the Info manual.

For example, with group definitions:

(defgroup c nil
  :link '(custom-manual "(ccmode)"))

(defgroup cpp nil
  :group 'c)

the customization buffer of the `cpp' group has the link to the Info
manual "ccmode".  The customization buffer of the `c' group has the
same link too.

> What in the source code produces such a link?

The function `custom-add-parent-links' in cus-edit.el:

    (and (null (get name 'custom-links)) ;No links of its own.
         (= (length parents) 1)         ;A single parent.
         (let* ((links (get (car parents) 'custom-links))
                (many (> (length links) 2)))
           (when links
             (insert "\nParent documentation: ")
             (while links
               (push (widget-create-child-and-convert widget (car links))
               ...

adds a link to the manual from the parent, if the group has no own links.

There is nothing bad not having a parent documentation link, since the
user can go to the parent group, and find the same link in the parent
customization buffer.

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