      /**
       * The constants used in this Content Widget.
       */
      public static interface CwConstants extends Constants,
          ContentWidget.CwConstants {
        String[] cwRadioButtonColors();

        String cwRadioButtonDescription();

        String cwRadioButtonName();

        String cwRadioButtonSelectColor();

        String cwRadioButtonSelectSport();

        String[] cwRadioButtonSports();
      }

      /**
       * An instance of the constants.
       */
      private CwConstants constants;

      /**
       * Initialize this example.
       */
      @Override
      public Widget onInitialize() {
        // Create a vertical panel to align the radio buttons
        VerticalPanel vPanel = new VerticalPanel();
        vPanel.add(new HTML(constants.cwRadioButtonSelectColor()));

        // Add some radio buttons to a group called 'color'
        String[] colors = constants.cwRadioButtonColors();
        for (int i = 0; i < colors.length; i++) {
          String color = colors[i];
          RadioButton radioButton = new RadioButton("color", color);
          radioButton.ensureDebugId("cwRadioButton-color-" + color);
          if (i == 2) {
            radioButton.setEnabled(false);
          }
          vPanel.add(radioButton);
        }

        // Add a new header to select your favorite sport
        vPanel.add(new HTML("<br>" + constants.cwRadioButtonSelectSport()));

        // Add some radio buttons to a group called 'sport'
        String[] sports = constants.cwRadioButtonSports();
        for (int i = 0; i < sports.length; i++) {
          String sport = sports[i];
          RadioButton radioButton = new RadioButton("sport", sport);
          radioButton.ensureDebugId("cwRadioButton-sport-"
              + sport.replaceAll(" ", ""));
          if (i == 2) {
            radioButton.setChecked(true);
          }
          vPanel.add(radioButton);
        }

        return vPanel;
      }