Dynamic TOC with an org subtree /element on a new window

Question

How can I set up a dynamic TOC with an org subtree on a new window? (TOC on the left, org heading and contents on the right.) The following functions by @blujay from

How can I get an org-mode outline in a 2nd buffer as a dynamic table of contents?

gets me most of the way there. Adding (org-narrow-to-element) or (org-narrow-to-subtree) to the second function (my/jump-to-point-and-show) opens the narrowed heading, but as I click through the headings in the TOC, subsequent headings don't open as expected. Also only the heading shows, but the contents stay collapsed unless I press TAB.

Here's the function from the StackExchange page linked above:

 (defun my/open-tree-view ()
  "Open a clone of the current buffer to the left, resize it to 30 columns, and bind <mouse-1> to jump to the same position in the base buffer."
  (interactive)
  (let ((new-buffer-name (concat "<tree>" (buffer-name))))
    ;; Create tree buffer
    (split-window-right 30)
    (if (get-buffer new-buffer-name)
        (switch-to-buffer new-buffer-name)  ; Use existing tree buffer
      ;; Make new tree buffer
      (progn  (clone-indirect-buffer new-buffer-name nil t)
              (switch-to-buffer new-buffer-name)
              (read-only-mode)
              (hide-body)
              (toggle-truncate-lines)

              ;; Do this twice in case the point is in a hidden line
              (dotimes (_ 2 (forward-line 0)))

              ;; Map keys
              (use-local-map (copy-keymap outline-mode-map))
              (local-set-key (kbd "q") 'delete-window)
              (mapc (lambda (key) (local-set-key (kbd key) 'my/jump-to-point-and-show))
                    '("<mouse-1>" "RET"))))))

(defun my/jump-to-point-and-show ()
  "Switch to a cloned buffer's base buffer and move point to the cursor position in the clone."
  (interactive)
  (let ((buf (buffer-base-buffer)))
    (unless buf
      (error "You need to be in a cloned buffer!"))
    (let ((pos (point))
          (win (car (get-buffer-window-list buf))))
      (if win
          (select-window win)
        (other-window 1)
        (switch-to-buffer buf))
      (goto-char pos)
      (when (invisible-p (point))
        (show-branches)))))

(I would also like to thank @blujay for the code snippets.)

Answer 1

I forgot to first widen the narrowed org element before applying the second function again. Adding widen, olivetti-mode, org-narrow-to-element, and org-show-chidren does the job. Changes made to the second function:

      (widen)
      (goto-char pos)  
      (olivetti-mode 1)
      (org-narrow-to-element) 
      (org-show-children)

Once again, many thanks to @blujay. As a non-programmer, I had been struggling to get this right for a while.

Comments: (org-narrow-to-element) messes up the next heading in the TOC. I suggest using (org-narrow-to-subtree) instead. I'm leaving the above code unchanged to highlight this (i.e., my) mistake.