+;;;; Window tree functions.
+
+(defun one-window-p (&optional nomini all-frames)
+ "Returns non-nil if the selected window is the only window (in its frame).
+Optional arg NOMINI non-nil means don't count the minibuffer
+even if it is active.
+
+The optional arg ALL-FRAMES t means count windows on all frames.
+If it is `visible', count windows on all visible frames.
+ALL-FRAMES nil or omitted means count only the selected frame,
+plus the minibuffer it uses (which may be on another frame).
+If ALL-FRAMES is neither nil nor t, count only the selected frame."
+ (let ((base-window (selected-window)))
+ (if (and nomini (eq base-window (minibuffer-window)))
+ (setq base-window (next-window base-window)))
+ (eq base-window
+ (next-window base-window (if nomini 'arg) all-frames))))
+
+(defun walk-windows (proc &optional minibuf all-frames)
+ "Cycle through all visible windows, calling PROC for each one.
+PROC is called with a window as argument.
+
+Optional second arg MINIBUF t means count the minibuffer window even
+if not active. MINIBUF nil or omitted means count the minibuffer iff
+it is active. MINIBUF neither t nor nil means not to count the
+minibuffer even if it is active.
+
+Several frames may share a single minibuffer; if the minibuffer
+counts, all windows on all frames that share that minibuffer count
+too. Therefore, when a separate minibuffer frame is active,
+`walk-windows' includes the windows in the frame from which you
+entered the minibuffer, as well as the minibuffer window. But if the
+minibuffer does not count, only windows from WINDOW's frame count.
+
+ALL-FRAMES is the optional third argument.
+ALL-FRAMES nil or omitted means cycle within the frames as specified above.
+ALL-FRAMES = `visible' means include windows on all visible frames.
+ALL-FRAMES = 0 means include windows on all visible and iconified frames.
+ALL-FRAMES = t means include windows on all frames including invisible frames.
+Anything else means restrict to WINDOW's frame."
+ ;; If we start from the minibuffer window, don't fail to come back to it.
+ (if (window-minibuffer-p (selected-window))
+ (setq minibuf t))
+ (let* ((walk-windows-start (selected-window))
+ (walk-windows-current walk-windows-start))
+ (while (progn
+ (setq walk-windows-current
+ (next-window walk-windows-current minibuf all-frames))
+ (funcall proc walk-windows-current)
+ (not (eq walk-windows-current walk-windows-start))))))
+
+(defun minibuffer-window-active-p (window)
+ "Return t if WINDOW (a minibuffer window) is now active."
+ (eq window (active-minibuffer-window)))
+
+(defmacro save-selected-window (&rest body)
+ "Execute BODY, then select the window that was selected before BODY."
+ (list 'let
+ '((save-selected-window-window (selected-window)))
+ (list 'unwind-protect
+ (cons 'progn body)
+ (list 'select-window 'save-selected-window-window))))
+\f