anchor.diff:  (defun floating-window-p (window)
     (typep window 'floating-window))
   
  +;;; header-window
   (defclass header-window (window) ())
   
   (defmethod initialize-instance ((window header-window) &key &allow-other-keys)
  
positive.code:   (clear-screens-of-window-list)
    (redraw-display))
  
  (defvar *in-redraw-display* nil
    "この変数がTの場合、redraw-display関数で画面を描画中であることを表します。
  再帰的なredraw-displayの呼び出しを防ぐために用います。")
  
  (defun redraw-display (&optional force)
    (when *in-redraw-display*
  
negative.code:     (mapc #'clear-screen (window-list))
      (mapc #'clear-screen (frame-floating-windows (current-frame)))))
  
  (defun window-view (window)
    (screen-view (window-screen window)))
  
  