code: public static void setPreferredRoadInternColor(Integer color) {
  		final Preferences prefs = Preferences.userNodeForPackage(RoadNetworkLayerConstants.class);
  		if (prefs != null) {
  			if (color == null) {
  				prefs.remove("ROAD_INTERN_COLOR"); //$NON-NLS-1$
  			} else {
  				prefs.put("ROAD_INTERN_COLOR", Integer.toString(color.intValue())); //$NON-NLS-1$
  			}
  			try {
  				prefs.flush();
  			} catch (BackingStoreException exception) {
  				//
  			}
  		}
  	}
docs: Set the color of the internal data structures used when they
  are drawn on the displayers.
  
  @param color is the color of the internal data structures, never <code>null</code>.