code: protected void ensureOpenCloseAdditionalInfo() {
  
          if (m_openClose == null) {
              m_openClose = new CmsPushButton(I_CmsButton.TRIANGLE_RIGHT, I_CmsButton.TRIANGLE_DOWN);
              m_openClose.setButtonStyle(ButtonStyle.FONT_ICON, null);
              m_openClose.setSize(Size.small);
              m_titleBox.insert(m_openClose, 0);
              m_openClose.addClickHandler(new ClickHandler() {
  
                  /**
                   * @see com.google.gwt.event.dom.client.ClickHandler#onClick(com.google.gwt.event.dom.client.ClickEvent)
                   */
                  public void onClick(ClickEvent event) {
  
                      setAdditionalInfoVisible(!getElement().getClassName().contains(CmsListItemWidget.OPENCLASS));
                      CmsDomUtil.resizeAncestor(CmsListItemWidget.this);
                  }
              });
          }
      }
docs: Ensures the open close button for the additional info list is present.<p>