anchor.diff:     (light     :light
   	      :width 30
   	      :normal +red+
  -	      :highlighted +orange+
  +	      :highlighted +gold1+
   	      :pushed-and-highlighted +green+)
      (radio-box (with-radio-box ()
                   (radio-box-current-selection
                    (make-color-chooser-toggle-button 'red +red+ "R" 'callback-red))
  -                (make-color-chooser-toggle-button 'orange +orange+ "O" 'callback-orange)
  +                (make-color-chooser-toggle-button 'yellow +gold1+ "Y" 'callback-yellow)
                   (make-color-chooser-toggle-button 'green +green+ "G" 'callback-green)))
      (time-left text-field
                 :editable-p nil
  
positive.code: ;;; possibilites :
  ;;; 1 - Click on a toggle-button : the color of the light-pane
  ;;;     will change
  ;;; 2 - Click on the orange or green toggle-button, then move your
  ;;;     mouse-pointer on the light-pane, and wait a few seconds.
  
  (in-package :clim-internals)
  
negative.code:            (simulate-user-action (find-pane-named *application-frame* 'red)))
  	  ((string= label "G")
             (traffic-pause 5)
             (simulate-user-action (find-pane-named *application-frame* 'yellow)))
  	  (t nil))))
  
  (defun traffic-pause (time)
  