backward-other-window Emacs
ふぇみにん日記から
http://kazuhiko.tdiary.net/20040102.html#p02
(defun backward-other-window (arg &optional all-frames)
"Select AEG'th different window on this frame, going backwards.
This is just like calling `other-window' with ARG negated."
(interactive "p")
(other-window (- arg) all-frames))
(global-set-key "\C-xO" 'backward-other-window)
Emacs21で使えました。便利