code: function (type, args, obj) {
              var container = args[0];
  
              if (typeof container == 'string') {
                  this.cfg.setProperty("container", document.getElementById(container), true);
              }
          }
docs: The default event handler fired when the "container" property
  is changed.
  @method configContainer
  @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.