docs: public void initEventHandlers(final CmsSitemapTreeNode node) {
  
          node.getOpener().addClickListener(new ClickListener() {
  
              private static final long serialVersionUID = 1L;
  
              public void buttonClick(ClickEvent event) {
  
                  CmsSitemapTreeController.this.onClickOpen(node);
              }
          });
      }