master de06e05: Make the lambda/closure buttons in `C-h b' say what they do

[Lars Ingebrigtsen]

branch: master
commit de06e0539537a99e147cbb96ee9fceaecafc9190
Author: Lars Ingebrigtsen <larsi@gnus.org>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Make the lambda/closure buttons in `C-h b' say what they do
    
    * lisp/button.el (buttonize): Add a help-echo property.
    
    * lisp/help.el (help--describe-command): Say what the
    lambda/closure buttons do.
---
 lisp/button.el | 7 +++++--
 lisp/help.el   | 3 ++-
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/lisp/button.el b/lisp/button.el
index f166aa5..e3f91cb 100644
--- a/lisp/button.el
+++ b/lisp/button.el
@@ -618,14 +618,17 @@ button at point is the button to describe."
 
 (define-obsolete-function-alias 'button-buttonize #'buttonize "29.1")
 
-(defun buttonize (string callback &optional data)
+(defun buttonize (string callback &optional data help-echo)
   "Make STRING into a button and return it.
 When clicked, CALLBACK will be called with the DATA as the
 function argument.  If DATA isn't present (or is nil), the button
-itself will be used instead as the function argument."
+itself will be used instead as the function argument.
+
+If HELP-ECHO, use that as the `help-echo' property."
   (propertize string
               'face 'button
               'mouse-face 'highlight
+              'help-echo help-echo
               'button t
               'follow-link t
               'category t
diff --git a/lisp/help.el b/lisp/help.el
index 2a72656..b2772f4 100644
--- a/lisp/help.el
+++ b/lisp/help.el
@@ -1347,7 +1347,8 @@ Return nil if the key sequence is too long."
                           (symbol-name (car definition))
                           (lambda (_)
                             (pp-display-expression
-                             definition "*Help Source*" t))))))
+                             definition "*Help Source*" t))
+                          nil "View definition"))))
         (t
          (insert "??\n"))))