anchor.diff:  (defbinding display-close (&optional (display (display-get-default))) nil
     (display display))
   
  +(defbinding flush () nil)
  +
   (defbinding display-get-event
       (&optional (display (display-get-default))) event
     (display display))
  
positive.code:     `(progn
         (threads-enter)
         (unwind-protect
  	   ,@body
  	 (threads-leave t)))))
  
negative.code:   (display display))
  
  (defun find-display (name)
    (if (not name)
        (display-get-default)
      (find name (list-displays) :key #'display-name :test #'string=)))
  
  (defun ensure-display (display)
    (etypecase display
      (null (display-get-default))
      (display display)
      (string (or (find-display display) (display-open display)))))
  
  
  ;;; Display manager
  