code: function (element) {
              var oHeader = this.header || (this.header = createHeader());
  
              oHeader.appendChild(element);
  
              this.changeHeaderEvent.fire(element);
              this.changeContentEvent.fire();
  
          }
docs: Appends the passed element to the header. If no header is present,
  one will be automatically created.
  @method appendToHeader
  @param {HTMLElement | DocumentFragment} element The element to
  append to the header. In the case of a document fragment, the
  children of the fragment will be appended to the header.