anchor.diff:  	    data))
   
   (defmacro with-alu ((stream alu) &body body)
  -  #+clim `(with-drawing-options (,stream :ink ,alu) ,@body)
  -  #-clim `(let ((.old. (scl:send ,stream :char-aluf))
  -		(.new. #-clim (if (eq ,alu :draw) tv:alu-ior ,alu)
  -		       #+clim ,alu))
  -	    (unwind-protect
  -		(progn (scl:send-if-handles ,stream :set-char-aluf .new.) ,@body)
  -	      (scl:send-if-handles ,stream :set-char-aluf .old.))))
  +  `(with-drawing-options (,stream :ink ,alu) ,@body))
   
   (defmethod display-data ((self essential-graph-data-map-mixin) STREAM graph)
     "Display the data on graph GRAPH using DATUM-DISPLAYER."
  
positive.code: 			   (funcall displayer stream x y datum)
  			   ;; Forcing the x buffer is nice here, but it is
  			   ;; extremely expensive.  It slows drawing by 4x.
  			   #+slow (force-output stream)))
  		(data self)))))
  
  (defmethod datum-displayer ((self essential-graph-data-map-mixin) graph)
  
negative.code: ;;; Clim 1.0 requires this be defined before any presentation type
  ;;; that depends on it.  Hence moved here from present.lisp.
  
  (defvar *repainting-dataset* nil)
  
  (defclass presentable-mixin
      ()
  