I think this might be a simpler approach. what you want (I think) is to leverage font-lock on tooltips to set a help-echo function instead of a string. You can override org-activate-footnote-links with an advice (which makes it easy to undo of you need). The tooltip function then looks up the tooltip when you ask for it. The 3 pieces are below. the first function looks up and returns a tooltip. the second is a lightly modified version of org-activate-footnote-links which just replaces the footnote reference string with the first function. the last piece is the override advice. you could use a minor mode to toggle the advice on and off.




#+BEGIN_SRC emacs-lisp
(defun footnote-reference-tooltip (_win _obj position)
  "Get footnote contents"
  (save-excursion
    (goto-char position)
    (let* ((fnf (org-element-context))
  (label (org-element-property :label fnf))
  (p (nth 1 (org-footnote-get-definition label))))
      (when p
(goto-char p)))    
    (let ((fnd (org-element-context)))
      (string-trim
       (buffer-substring (org-element-property :contents-begin fnd)
(org-element-property :contents-end fnd))))))


(defun footnote-tooltip (limit)
  "Add text properties for footnotes."
  (let ((fn (org-footnote-next-reference-or-definition limit)))
    (when fn
      (let* ((beg (nth 1 fn))
    (end (nth 2 fn))
    (label (car fn))
    (referencep (/= (line-beginning-position) beg)))
(when (and referencep (nth 3 fn))
 (save-excursion
   (goto-char beg)
   (search-forward (or label "fn:"))
   (org-remove-flyspell-overlays-in beg (match-end 0))))
(add-text-properties beg end
    (list 'mouse-face 'highlight
  'keymap org-mouse-map
  'help-echo
  (if referencep #'footnote-reference-tooltip
    "Footnote definition")
  'font-lock-fontified t
  'font-lock-multiline t
  'face 'org-footnote))))))

(advice-add 'org-activate-footnote-links :override 'footnote-tooltip)
#+END_SRC


John

-----------------------------------
John Kitchin (he/his)
Professor
Doherty Hall A207F
Department of Chemical Engineering
Carnegie Mellon University
Pittsburgh, PA 15213
412-268-7803
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On Wed, Feb 23, 2022 at 2:52 PM Juan Manuel Macías <maciaschain@posteo.net> wrote:
Hi Samuel,

Samuel Wales writes:

> what a great idea.  i am interested in your comments.  emacs has lots
> of tooltip-related features.  eldoc, help-at-pt, mouse-avoidance, etc.
> you don't want tooltips when your mouse happens to end up over.  or
> for your mouse to go haywire just because you ended up over.  i ran
> into a lot of confusion with various mechanisms.
>
> [e.g. i like having tooltips in echo area, and don't like eldoc for
> function sigs, and do want cursor/mouse consistency.]
>
> i found that some tooltip features actually break others.  just
> wondering if you noticed this and what you think of it.

I don't have much experience with Emacs tooltips and I haven't studied
them much, because I hardly use the mouse in Emacs :-) But I noticed
that you can also display the content of a tooltip in the echo area,
with `<C-h .>' (`display-local-help'), or even set to non-nil
`help-at-pt-display-when-idle' and evaluate `help-at-pt-set-timer', so
that a tootltip is displayed at point; and in this scenario, they can be
useful to me to quickly have some type of information.

You can also set this variable to force tooltips always in the echo
area:

(setq tooltip-use-echo-area t)

Anyway, I haven't given up on the idea of footnote tooltips yet. Here's
a new version of the code I attached in my first post in this thread,
and I think it's simpler now and works better, though I don't know if it
might have any side effects... Footnote tooltips are activated with the
minor mode `my-org-fn-tooltip-mode'.

A new demo video:

https://cloud.disroot.org/s/sBGJjCzbYgYbn5k

Best regards,

Juan Manuel