anchor.diff:          (win-width (widget-width stream))
           (win-height (widget-height stream))
           (colour (window-background-colour stream)))
  +    (setf start-y (- start-y (cursor-line stream))
  +          end-y (- end-y (cursor-line stream)))
       (cond ((eql start-y end-y)
              ;; Clearing one line.
              (bitset 16 (- end-x start-x) colour framebuffer (+ (widget-y stream) start-y) (+ (widget-x stream) start-x)))
  
positive.code:   (check-type x integer)
    (check-type y integer)
    (setf (cursor-x stream) x
          (cursor-y stream) y))
  
  (defmethod sys.int::stream-move-to ((stream text-window) x y)
    (sys.int::stream-move-to (text-window-display stream) x y))
  
negative.code: (defclass text-widget (sys.gray:fundamental-character-output-stream)
    ((cursor-x :initarg :cursor-x :accessor cursor-x)
     (cursor-y :initarg :cursor-y :accessor cursor-y)
     (line :initarg :line :accessor cursor-line)
     (foreground :initarg :foreground :accessor window-foreground-colour)
     (background :initarg :background :accessor window-background-colour)
     (framebuffer :initarg :framebuffer :reader framebuffer)
  