anchor.diff:        (when (> rotation 180)
   	(setq rotation (- rotation 360)))
         (update-tilt))
  +
  +    (defun tilt-key-event (e)
  +      (case (@ e which)
  +	(37 (left))
  +	(38 (up))
  +	(39 (right))
  +	(40 (down))))
       
       (defun init-tilt-controls ()
         "Initialize tilt controls for tilting/rotating the sail"
  
positive.code: 	    rotation 0
  	    absorbed 100)
        ;; Arrow key events
        ((@ ($ (@ document body)) on) "keydown"
         #'(lambda (e)
  	   (case (@ e which)
  	     (37 (left))
  	     (38 (up))
  	     (39 (right))
  	     (40 (down)))))
        ;; Clicking on arrow images
        ((@ ($ "#up") click) #'(lambda (e) (up)))
        ((@ ($ "#down") click) #'(lambda (e) (down)))
  
negative.code:       ;; Pause button event
        (let ((pause-html ($ "#pause")))
  	((@ pause-html click)
  	 #'toggle-pause))
        ;; Pause with spacebar
        ((@ ($ (@ document body)) keydown)
         #'space-pause-event)
        ;; Reset button
        (let ((reset-html ($ "#reset")))
  	((@ reset-html click)
  	 #'(lambda (e)
  	     (reset-absorb-force)
  	     (update-absorb-force)))))
      
      (defun animate-force ()
        (request-animation-frame animate-force)
        (unless pause
  