For a more generic answer dealing with emacs' windows, you can look at windmove, which started shipping with Emacs circa Emacs 22, I believe:
;;; Commentary:
;;
;; This package defines a set of routines, windmove-{left,up,right,
;; down}, for selection of windows in a frame geometrically. For
;; example, `windmove-right' selects the window immediately to the
;; right of the currently-selected one. This functionality is similar
;; to the window-selection controls of the BRIEF editor of yore.
;;
;; One subtle point is what happens when the window to the right has
;; been split vertically; for example, consider a call to
;; `windmove-right' in this setup:
;;
;; -------------
;; | | A |
;; | | |
;; | |-----
;; | * | | (* is point in the currently
;; | | B | selected window)
;; | | |
;; -------------
;;
;; There are (at least) three reasonable things to do:
;; (1) Always move to the window to the right of the top edge of the
;; selected window; in this case, this policy selects A.
;; (2) Always move to the window to the right of the bottom edge of
;; the selected window; in this case, this policy selects B.
;; (3) Move to the window to the right of point in the selected
;; window. This may select either A or B, depending on the
;; position of point; in the illustrated example, it would select
;; B.
;;
;; Similar issues arise for all the movement functions. Windmove
;; resolves this problem by allowing the user to specify behavior
;; through a prefix argument. The cases are thus:
;; * if no argument is given to the movement functions, or the
;; argument given is zero, movement is relative to point;
;; * if a positive argument is given, movement is relative to the top
;; or left edge of the selected window, depending on whether the
;; movement is to be horizontal or vertical;
;; * if a negative argument is given, movement is relative to the
;; bottom or right edge of the selected window, depending on whether
;; the movement is to be horizontal or vertical.