code: function (event) {
          event = normalizeEvent(this.dom, event);
  
          var element = event.toElement || event.relatedTarget;
          if (element !== this.dom) {
              while (element && element.nodeType !== 9) {
                  // 忽略包含在root中的dom引起的mouseOut
                  if (element === this.dom) {
                      return;
                  }
  
                  element = element.parentNode;
              }
          }
  
          this.trigger('mouseout', event);
      }
docs: Mouse out handler
  @inner
  @param {Event} event