Display local date for Mew message

mew-local-date.el

(defvar mew-my-message-date-overlay nil)

(defun mew-my-message-date-overlay ()
  (or
   mew-my-message-date-overlay 
   (setq mew-my-message-date-overlay 
         (make-overlay (point-min) (point-min)))))

(defun mew-my-message-display-local-date ()
  (condition-case err
      (save-excursion
        (goto-char (point-min))
        (when (re-search-forward (concat "^" mew-date: " *\\(.*\\)") nil t)
          (let* ((original (match-string 1))
                 (start (match-beginning 1))
                 (end (match-end 1))
                 (ov (mew-my-message-date-overlay))
                 (time (parse-time-string original))
                 (orig-tz (nth 8 time))
                 (tz (nth 8 (decode-time (current-time))))
                 (date (apply 'encode-time time))
                 (local (mew-time-ctz-to-rfc date)))
            (unless (equal orig-tz tz)
              (let ((new (format "%s == %s" original local)))
                (move-overlay ov start end (current-buffer))
                (overlay-put ov 'display new))))))
    (error
     (message "%s" err))))

(add-hook 'mew-message-hook 'mew-my-message-display-local-date)