anchor.diff:  	     (setf projection (projection corners))
   	     ((@ scene add) projection)
   	     ;; Update absorbed arrow
  -	     ((@ absorb-arrow set-length) (* 10 (/ absorbed 100)))))
  +	     (let ((l (* 10 (/ absorbed 100))))
  +	       ((@ absorb-arrow set-length) l)
  +	       ((@ absorb-arrow position set-y) (- l)))))
   	 )
   	;; Add objects
   	((@ sail add) mirror)
  
positive.code: 	 (let ((init-super ((@ app superior) "init")))
  	   (lambda ()
  	     (funcall init-super)
  	     ((@ sail-position add) absorb-arrow)))
  	 ))
        app)
      
  
negative.code:       app)
  
      (defun add-absorb-force (app)
        (with-slots (accelfn incidence absorb-force-arrow sail init sail-position incident origin update-tilt absorbed) app
  	(setf
  	 absorb-force-arrow
  	 (new (3fn *arrow-helper incident origin 10 0xff0000))
  	 accelfn
  	 (lambda ()
  	   (let ((accel (* 5d-5 (abs (cos (* incidence (/ pi 180)))))))
  