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

        String cwHorizontalPanelDescription();

        String cwHorizontalPanelName();
      }

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

      /**
       * Initialize this example.
       */
      @Override
      public Widget onInitialize() {
        // Create a Horizontal Panel
        HorizontalPanel hPanel = new HorizontalPanel();
        hPanel.setSpacing(5);

        // Add some content to the panel
        for (int i = 1; i < 5; i++) {
          hPanel.add(new Button(constants.cwHorizontalPanelButton() + " " + i));
        }

        // Return the content
        hPanel.ensureDebugId("cwHorizontalPanel");
        return hPanel;
      }