code: function (type, args, obj) {
  
              var zIndex = args[0],
                  el = this.element;
  
              if (! zIndex) {
                  zIndex = Dom.getStyle(el, "zIndex");
                  if (! zIndex || isNaN(zIndex)) {
                      zIndex = 0;
                  }
              }
  
              if (this.iframe || this.cfg.getProperty("iframe") === true) {
                  if (zIndex <= 0) {
                      zIndex = 1;
                  }
              }
  
              Dom.setStyle(el, "zIndex", zIndex);
              this.cfg.setProperty("zIndex", zIndex, true);
  
              if (this.iframe) {
                  this.stackIframe();
              }
          }
docs: The default event handler fired when the "zIndex" property is changed.
  @method configzIndex
  @param {String} type The CustomEvent type (usually the property name)
  @param {Object[]} args The CustomEvent arguments. For configuration
  handlers, args[0] will equal the newly applied value for the property.
  @param {Object} obj The scope object. For configuration handlers,
  this will usually equal the owner.