anchor.diff:  (define-presentation-type menu-item ())
   
   (define-presentation-method presentation-typep (object (type menu-item))
  -  (declare (ignore object type))
  +  (declare (ignore object))
     t)
   
   (defmethod menu-choose
  
positive.code:                    id-test cache-value cache-test default-presentation))
    (with-room-for-graphics (menu :first-quadrant nil)
      (funcall drawer menu presentation-type))
    
    (adjust-menu-size-and-position
     menu
     :x-position x-position
  
negative.code:     (let ((*pointer-documentation-output* pointer-documentation))
        (handler-case
            (with-input-context (`(or ,presentation-type blank-area) :override t)
                (object type event)
                (prog1 nil (loop (read-gesture :stream menu)))
              (blank-area nil)
              (t (values object event)))
  