bug#5474: 23.1.91.1; describe-mode does not offer link to the .el

[Juri Linkov]

> We hit C-h m. We see the following:
>
>   XXXX mode:
>   Major mode for editing XXXX.
>
>   key             binding
>   ---             -------
>
>   C-c         Prefix Command
>   ESC         Prefix Command
>
>   C-M-x               XXXX-eval-defun
>
> Nowhere is there a link to XXXX.el.
> We have to hit XXXX-eval-defun to get a link to XXXX.el.
>
> It should say at top
>   XXXX mode:
>   Major mode for editing XXXX. Defined in XXXX.el <---clickable.
>
> Or
>   XXXX mode (... XXXX-mode, defined in XXXX.el):
>   Major mode for editing XXXX.

This can be implemented after feature freeze with the following patch
that adds links to the major/minor mode names for `C-h m':

Index: emacs/lisp/help.el
===================================================================
RCS file: /sources/emacs/emacs/lisp/help.el,v
retrieving revision 1.327
diff -u -r1.327 help.el
--- emacs/lisp/help.el  21 Mar 2007 16:15:45 -0000      1.327
+++ emacs/lisp/help.el  5 May 2007 17:01:30 -0000
@@ -815,7 +815,12 @@
                  (princ "\n\f\n")
                  (push (point-marker) help-button-cache)
                  ;; Document the minor modes fully.
-                 (insert pretty-minor-mode)
+                 (insert-button pretty-minor-mode
+                                'action `(lambda (button)
+                                           (describe-function ',mode-function))
+                                'follow-link t
+                                'help-echo (format "mouse-2, RET: show 
information about %S"
+                                                   mode-function))
                  (princ (format " minor mode (%s):\n"
                                 (if (zerop (length indicator))
                                     "no indicator"
@@ -833,10 +838,15 @@
 
          (princ "\n(Information about these minor modes follows the major mode 
info.)\n\n"))
        ;; Document the major mode.
-       (let ((mode mode-name))
+       (let ((major-mode-function major-mode) (mode mode-name))
          (with-current-buffer standard-output
             (let ((start (point)))
-              (insert (format-mode-line mode))
+             (insert-button (format-mode-line mode)
+                            'action `(lambda (button)
+                                       (describe-function 
',major-mode-function))
+                            'follow-link t
+                            'help-echo (format "mouse-2, RET: show information 
about %S"
+                                               major-mode-function))
               (add-text-properties start (point) '(face bold)))))
        (princ " mode:\n")
        (princ (documentation major-mode)))

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