bug#22870: 25.0.91; Mouse-clicks fail on button overlays with display properties

bug#22870: 25.0.91; Mouse-clicks fail on button overlays with display properties

[Artur Malabarba]

1. Visit the scratch buffer.

2. Evaluate this code:

(defun my-action (&rest _)
  (interactive)
  (message "WORKED!"))

(make-button (point-min) (+ 30 (point-min))
             'display "..."
             'action #'my-action
             'follow-link t)

3. As expected, the first 30 chars of the buffer will be hidden under a
button that displays as “...”.  Hitting RET on that buffer works as
expected (you see the message “Worked!” on the echo-area).

4. Try clicking on the button with the mouse. You'll get the following error:

Debugger entered--Lisp error: (void-function nil)
  nil(("..." . 1))
  button-activate(("..." . 1) t)
  push-button((mouse-2 (#<window 3 on *scratch*> 1 (14 . 2) 15461622 ("..." . 1) 1 (1 . 0) nil (5 . 2) (9 . 18))))
  funcall-interactively(push-button (mouse-2 (#<window 3 on *scratch*> 1 (14 . 2) 15461622 ("..." . 1) 1 (1 . 0) nil (5 . 2) (9 . 18))))
  call-interactively(push-button nil nil)
  command-execute(push-button)

5. Adding a `mouse-action' property makes no difference.

6. Without the `display' property, everything works as expected.



Looks like this happens because the first argument given to
`button-activate' is `("..." . 1)', while it should be the overlay.

bug#22870: 25.0.91; Mouse-clicks fail on button overlays with display properties

[Stefan Kangas]

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Artur Malabarba <bruce.connor.am@gmail.com> writes:

> 1. Visit the scratch buffer.
>
> 2. Evaluate this code:
>
> (defun my-action (&rest _)
>   (interactive)
>   (message "WORKED!"))
>
> (make-button (point-min) (+ 30 (point-min))
>              'display "..."
>              'action #'my-action
>              'follow-link t)
>
> 3. As expected, the first 30 chars of the buffer will be hidden under a
> button that displays as “...”.  Hitting RET on that buffer works as
> expected (you see the message “Worked!” on the echo-area).
>
> 4. Try clicking on the button with the mouse. You'll get the following
error:
>
> Debugger entered--Lisp error: (void-function nil)
>   nil(("..." . 1))
>   button-activate(("..." . 1) t)
>   push-button((mouse-2 (#<window 3 on *scratch*> 1 (14 . 2) 15461622
("..." . 1) 1 (1 . 0) nil (5 . 2) (9 . 18))))
>   funcall-interactively(push-button (mouse-2 (#<window 3 on *scratch*> 1
(14 . 2) 15461622 ("..." . 1) 1 (1 . 0) nil (5 . 2) (9 . 18))))
>   call-interactively(push-button nil nil)
>   command-execute(push-button)
>
> 5. Adding a `mouse-action' property makes no difference.
>
> 6. Without the `display' property, everything works as expected.
>
>
>
> Looks like this happens because the first argument given to
> `button-activate' is `("..." . 1)', while it should be the overlay.

It seems like it was broken by this commit:
24fc948039 2012-12-06 * lisp/button.el: Make them work in header-lines.

Best regards,
Stefan Kangas

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bug#22870: 25.0.91; Mouse-clicks fail on button overlays with display properties

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Wed, 9 Oct 2019 18:21:22 +0200
> Cc: 22870@debbugs.gnu.org
> 
> > Looks like this happens because the first argument given to
> > `button-activate' is `("..." . 1)', while it should be the overlay.
> 
> It seems like it was broken by this commit:
> 24fc948039 2012-12-06 * lisp/button.el: Make them work in header-lines.

Can you sport which part(s) of that change broke this?

Thanks.

bug#22870: 25.0.91; Mouse-clicks fail on button overlays with display properties

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

> > It seems like it was broken by this commit:
> > 24fc948039 2012-12-06 * lisp/button.el: Make them work in header-lines.
>
> Can you sport which part(s) of that change broke this?

Yes, this part:

@@ -417,11 +444,13 @@ push-button
       ;; POS is a mouse event; switch to the proper window/buffer
       (let ((posn (event-start pos)))
        (with-current-buffer (window-buffer (posn-window posn))
-     (push-button (posn-point posn) t)))
+   (if (posn-area posn)
+       ;; mode-line or header-line event
+       (button-activate (car (posn-string posn)) t)
+     (push-button (posn-point posn)) t)))

(car (posn-string posn))  -- changed to (posn-string posn) in commit
4b0df8483 means that in button-activate, the following expression
returns nil:

(or (and use-mouse-action (button-get button 'mouse-action))
            (button-get button 'action))

Best regards,
Stefan Kangas

bug#22870: 25.0.91; Mouse-clicks fail on button overlays with display properties

[Lars Ingebrigtsen]

Artur Malabarba <bruce.connor.am@gmail.com> writes:

> 1. Visit the scratch buffer.
>
> 2. Evaluate this code:
>
> (defun my-action (&rest _)
>   (interactive)
>   (message "WORKED!"))
>
> (make-button (point-min) (+ 30 (point-min))
>              'display "..."
>              'action #'my-action
>              'follow-link t)
>
> 3. As expected, the first 30 chars of the buffer will be hidden under a
> button that displays as “...”.  Hitting RET on that buffer works as
> expected (you see the message “Worked!” on the echo-area).
>
> 4. Try clicking on the button with the mouse. You'll get the following error:
>
> Debugger entered--Lisp error: (void-function nil)
>   nil(("..." . 1))
>   button-activate(("..." . 1) t)
>   push-button((mouse-2 (#<window 3 on *scratch*> 1 (14 . 2) 15461622 ("..." . 1) 1 (1 . 0) nil (5 . 2) (9 . 18))))

I'm unable to reproduce this in Emacs 28, and I see that a change was
committed to the push-button command earlier this year, so I think this
has been fixed, and I'm closing this bug report.  If you can see this
bug in Emacs 28, please send a message to the debbugs address and we'll
reopen.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no