anchor.diff:      (let ((res +nowhere+))
         (loop for (r) in erase-overlapping do (setf res (region-union res r)))
         (loop for (r) in move-overlapping do (setf res (region-union res r)))
  -      (replay history stream res)) ))
  +      (replay history stream res))))
   
   (defclass updating-stream-state (complete-medium-state)
     ((cursor-x :accessor cursor-x :initarg :cursor-x :initform 0)
  
positive.code: 	    (t
  	     ;; It doesn't need to be updated, but it does go into the
  	     ;; parent's sequence of records
  	     (when *trace-updating-output*
  	       (format *trace-output* "clean ~S~%" record))
               ;;
               (multiple-value-bind (cx cy) (stream-cursor-position stream)
                 (multiple-value-bind (sx sy) (output-record-start-cursor-position record)
  
negative.code: 
  (declaim (inline hash-coords))
  (defun hash-coords (x1 y1 x2 y2)
    (declare (type coordinate x1 y1 x2 y2))
    (let ((hash-val 0))
        (declare (type fixnum hash-val))
        (labels ((rot4 (val)
  