bug#37515: 27.0.50; button.el doesn't support help-echo function

[Katsumi Yamaoka]

On Thu, 26 Sep 2019 10:14:52 +0900, Katsumi Yamaoka wrote:
> So, `forward-button' should be fixed to something like this:

The patch I posted last was incomplete.  Please replace it with:

--8<---------------cut here---------------start------------->8---
--- button.el~  2019-07-30 21:20:12.288879200 +0000
+++ button.el   2019-09-26 01:26:25.210300000 +0000
@@ -513,6 +513,9 @@
             nil
          (user-error (if wrap "No buttons!" "No more buttons")))
       (let ((msg (and display-message (button-get button 'help-echo))))
+       (when (functionp msg)
+         (setq msg (funcall msg (selected-window) (current-buffer)
+                            (button-start button))))
        (when msg
          (message "%s" msg)))
       button)))
--8<---------------cut here---------------end--------------->8---

Thanks.