gistfile1.el

;; http://www.bookshelf.jp/soft/meadow_30.html#SEC400
(defun swap-screen()
  "Swap two screen,leaving cursor at current window."
  (interactive)
  (let ((thiswin (selected-window))
        (nextbuf (window-buffer (next-window))))
    (set-window-buffer (next-window) (window-buffer))
    (set-window-buffer thiswin nextbuf)))
(defun swap-screen-with-cursor()
  "Swap two screen,with cursor in same buffer."
  (interactive)
  (let ((thiswin (selected-window))
        (thisbuf (window-buffer)))
    (other-window 1)
    (set-window-buffer thiswin (window-buffer))
    (set-window-buffer (selected-window) thisbuf)))

(define-key global-map (kbd "C-x m") 'swap-screen)