code: @UiHandler("m_opener")
      protected void handleClick(ClickEvent e) {
  
          if (m_animation != null) {
              m_animation.cancel();
          }
          if (!m_opened) {
  
              // show content
              setOpen(true);
  
              m_animation = CmsSlideAnimation.slideIn(m_content.getElement(), new Command() {
  
                  /**
                   * @see com.google.gwt.user.client.Command#execute()
                   */
                  public void execute() {
  
                      OpenEvent.fire(CmsFieldSet.this, CmsFieldSet.this);
                      CmsDomUtil.resizeAncestor(getParent());
                  }
              }, m_animationDuration);
          } else {
  
              // hide content
              m_animation = CmsSlideAnimation.slideOut(m_content.getElement(), new Command() {
  
                  /**
                   * @see com.google.gwt.user.client.Command#execute()
                   */
                  public void execute() {
  
                      setOpen(false);
                      CloseEvent.fire(CmsFieldSet.this, CmsFieldSet.this);
                      CmsDomUtil.resizeAncestor(getParent());
                  }
              }, m_animationDuration);
          }
      }
docs: Adds a click handler to the image icon of this fieldset.<p>
  
  On click the
  
  @param e the event