(goto-char new-start)
(insert "[ " button-label (if show " ]" " (hidden) ]"))
(set-text-properties new-start (point) properties)
(let ((old-end (button-end button)))
(move-overlay button new-start (point))
(delete-region (point) old-end))
(goto-char new-start)
(insert "[ " button-label (if show " ]" " (hidden) ]"))
(set-text-properties new-start (point) properties)
(let ((old-end (button-end button)))
(move-overlay button new-start (point))
(delete-region (point) old-end))