>>76
You can probably find something better but I now see what the narrowing is for. I think the following should only traverse the additional newline at the end of each paragraph a second time rather than the whole buffer, still it's not very elegant:
(defun sbbs--insert-sxml-par (sxml)
"Insert paragraph contents SXML at point."
(save-restriction
(narrow-to-region (1- (point)) (point))
(insert (sbbs--process-sxml sxml))
(let (beg)
(goto-char (point-min))
(while (setq beg (next-single-property-change (point) 'action))
;; Buttons use overlays that cannot be passed in
;; strings. Therefore whenever a `activity' property was inserted into
;; the buffer, `make-button' has to be called once more to add the
;; actual overlay.
(let ((end (or (next-single-property-change beg 'action) (point-max))))
(make-button beg end 'action (get-text-property beg 'action))
(goto-char end)))
(goto-char (point-max)))
(newline)))