anchor.diff:  
       (defun add-tilt (app)
         "Add tilt controls"
  -      (with-slots (scene camera mirror sail corners projection update-tilt tilt-update-fn rotation incidence absorbed incident absorb-arrow origin up down left right render visibility) app
  +      (with-slots (camera sail update-tilt tilt-update-fn rotation incidence absorbed up down left right render) app
   	;; Move the camera
   	((@ camera position set) -4 -6 6)
   	;; Set new slots
   	(setf
   	 rotation 0 incidence 0 absorbed 100
  -	 mirror (mirror)
  -	 corners (corners mirror)
  -	 projection (projection mirror)
  -	 incident (incident)
  -	 absorb-arrow (new (3fn *arrow-helper incident origin 10 0xffff00))
  -	 visibility
  -	 (let ((visibility-super ((@ app superior) "visibility")))
  -	   (lambda (bool)
  -	     (funcall visibility-super bool)
  -	     (setf (@ projection visible) bool
  -		   (@ absorb-arrow visible) bool)))
  -	 tilt-update-fn 
  +	 tilt-update-fn
   	 (lambda ()
   	   ;; Sail rotation matrix
   	   ((@ sail update-matrix-world))
  -	   ;; Corners of the sail
  -	   (setf corners (corners mirror))
  -	   ;; Projection
  -	   ((@ scene remove) projection)
  -	   (setf projection (projection mirror))
  -	   ((@ scene add) projection)
   	   ;; Angle fields
   	   (let ((inc-html (@ ($ "#incidence") 0)))
   	     (when inc-html
   	       (setf (@ inc-html inner-h-t-m-l) ((@ incidence to-string)))))
  -	   ;;(setf (@ ($ "#incidence") 0 inner-h-t-m-l) ((@ incidence to-string)))
   	   (let ((rot-html (@ ($ "#rotation") 0)))
   	     (when rot-html
   	       (setf (@ rot-html inner-h-t-m-l) ((@ rotation to-string)))))
  -	   ;;(setf (@ ($ "#rotation") 0 inner-h-t-m-l) ((@ rotation to-string)))
   	   (let ((absorbed-html (@ ($ "#absorbed") 0)))
   	     (when absorbed-html
  -	       (setf (@ absorbed-html inner-h-t-m-l) ((@ absorbed to-string)))))
  -	   ;; Update absorbed arrow
  -	   ((@ absorb-arrow set-length) (* 10 (/ absorbed 100))))
  +	       (setf (@ absorbed-html inner-h-t-m-l) ((@ absorbed to-string))))))
   	 update-tilt
   	 (lambda ()
   	   (funcall tilt-update-fn)
  
positive.code: 	((@ ($ "#down") click) #'(lambda (e) (funcall down)))
  	((@ ($ "#left") click) #'(lambda (e) (funcall left)))
  	((@ ($ "#right") click) #'(lambda (e) (funcall right)))
  	;; Add objects
  	((@ sail add) mirror)
  	((@ scene add) projection)
  	((@ scene add) absorb-arrow)
  	)
        app)
  
      (defun absorb ()
        "Absorbed light on a sail app"
        (add-tilt (what)))
  
      (defun add-reflection (app)
        (with-slots (absorbed normal incident reflectv reflection reflect-arrow mirror corners reflect-arrow tilt-update-fn origin scene visibility) app
  
negative.code: 		    (funcall load))))))
        app)
      
      (defun flightschool ()
        (add-sail (template)))
  
  