bug: Xemacs problem with editing headings with compressed contents

["Tim O'Callaghan" <tim.ocallaghan@gmail.com>]

Hi.

There is some problem with tags and headings. I've had instances where
the tag has disappeared or merged into my heading.

Repeatable with Xemacs 21.4.19 i586-pc-win32, org 5.22a using this fragment:
-----

* REAEARCH memory problems on oxo50                     :proj:
*** WAIT korstian to organise a meeting.
-----

If i try to add the S into the heading when it is folded, then it
generates the error "Visible portion of buffer not modifiable".
Debugger gives:

Debugger entered--Lisp error: (error "Visible portion of buffer not modifiable")
  move-to-column(70 t)
  (progn (setq tags (match-string 2)) (goto-char (match-beginning 1))
(insert " ") (delete-region (point) (1+ ...)) (backward-char 1)
(move-to-column (max ... ... ...) t) (insert tags) (move-to-column
(min ... col) t))
  (if (and (looking-at ...) (< pos ...)) (progn (setq tags ...)
(goto-char ...) (insert " ") (delete-region ... ...) (backward-char 1)
(move-to-column ... t) (insert tags) (move-to-column ... t))
(goto-char pos))
  (let ((pos ...) (col ...) tags) (beginning-of-line 1) (if (and ...
...) (progn ... ... ... ... ... ... ... ...) (goto-char pos)))
  org-align-tags-here(70)
  (if (and (equal ... ?*) (org-on-heading-p)) (org-align-tags-here
org-tags-column))
  (when (and (equal ... ?*) (org-on-heading-p)) (org-align-tags-here
org-tags-column))
  org-fix-tags-on-the-fly()
  (if (and (org-table-p) (progn ... t) (eq N 1) (looking-at "[^|\n]*
|")) (let (org-table-may-need-update) (goto-char ...)
(delete-backward-char 1) (goto-char ...) (self-insert-command N))
(setq org-table-may-need-update t) (self-insert-command N)
(org-fix-tags-on-the-fly))
  org-self-insert-command(1)
  call-interactively(org-self-insert-command)
  recursive-edit()
  debug(error (error "Visible portion of buffer not modifiable"))
  move-to-column(70 t)
  (progn (setq tags (match-string 2)) (goto-char (match-beginning 1))
(insert " ") (delete-region (point) (1+ ...)) (backward-char 1)
(move-to-column (max ... ... ...) t) (insert tags) (move-to-column
(min ... col) t))
  (if (and (looking-at ...) (< pos ...)) (progn (setq tags ...)
(goto-char ...) (insert " ") (delete-region ... ...) (backward-char 1)
(move-to-column ... t) (insert tags) (move-to-column ... t))
(goto-char pos))
  (let ((pos ...) (col ...) tags) (beginning-of-line 1) (if (and ...
...) (progn ... ... ... ... ... ... ... ...) (goto-char pos)))
  org-align-tags-here(70)
  (if (and (equal ... ?*) (org-on-heading-p)) (org-align-tags-here
org-tags-column))
  (when (and (equal ... ?*) (org-on-heading-p)) (org-align-tags-here
org-tags-column))
  org-fix-tags-on-the-fly()
  (if (and (org-table-p) (progn ... t) (eq N 1) (looking-at "[^|\n]*
|")) (let (org-table-may-need-update) (goto-char ...)
(delete-backward-char 1) (goto-char ...) (self-insert-command N))
(setq org-table-may-need-update t) (self-insert-command N)
(org-fix-tags-on-the-fly))
  org-self-insert-command(1)
  call-interactively(org-self-insert-command)

Tim.