anchor.diff:  (defvar *clip-rect-y* 0)
   (defvar *clip-rect-width* 0)
   (defvar *clip-rect-height* 0)
  +
  +(defun damage-whole-screen ()
  +  (setf *clip-rect-width* (mezzano.supervisor:framebuffer-width *main-screen*)
  +        *clip-rect-height* (mezzano.supervisor:framebuffer-height *main-screen*)
  +        *clip-rect-x* 0
  +        *clip-rect-y* 0))
   
   (defun expand-clip-rectangle (x y w h)
     (when (or (zerop *clip-rect-width*)
  
positive.code: 
  (defun recompose-windows (&optional full)
    (when full
      ;; Expand the cliprect to the entire screen.
      (setf *clip-rect-width* (mezzano.supervisor:framebuffer-width *main-screen*)
            *clip-rect-height* (mezzano.supervisor:framebuffer-height *main-screen*)
            *clip-rect-x* 0
            *clip-rect-y* 0))
    (when (or (zerop *clip-rect-width*)
              (zerop *clip-rect-height*))
      (return-from recompose-windows))
  
negative.code:     (when (and *m-tab-active*
                 (allow-m-tab win))
        (push win *m-tab-list*))
      (expand-clip-rectangle-by-window win)))
  
  (defmacro with-window ((window fifo width height &rest options) &body body)
    `(let (,window)
  