public ScreenCreditController(WorldWindow wwd)
        {
            if (wwd == null)
            {
                String msg = Logging.getMessage("nullValue.WorldWindow");
                Logging.logger().severe(msg);
                throw new ArgumentException(msg);
            }

            this.wwd = wwd;

            if (wwd.getSceneController().getScreenCreditController() != null)
            {
                wwd.getSceneController().getScreenCreditController().dispose();
            }

            wwd.getSceneController().setScreenCreditController(this);
            wwd.addSelectListener(this);
        }