anchor.diff:  
   (defun load-window-tree (dumped-tree)
     (dolist (window (window-list))
  -    (screen-delete (window-screen window)))
  +    (%free-window window))
     (let ((current-window nil))
       (labels ((f (dumped-tree)
                   (if (eq :window (car dumped-tree))
  
positive.code:          nil)
          (t t)))
  
  (defun dump-window-tree (window-tree current-window)
    (labels ((f (window-tree)
                (if (window-tree-leaf-p window-tree)
  
negative.code:       (if (null node2)
            (setf (window-tree) (funcall another-getter))
            (funcall setter2 (funcall another-getter)))))
    (when (window-delete-hook window)
      (funcall (window-delete-hook window)))
    (%free-window window)
    t)
  
  (defun collect-left-windows (window-list)
  