text: (function(){
  
    function setHeader(bar){
      return bar.xtag.header || (bar.xtag.header = xtag.queryChildren(bar, 'h1,h2,h3,h4,h5,h6')[0])
    }
  
    xtag.register('x-appbar', {
      lifecycle: {
        created: function(){
          setHeader(this);
        }
      },
      accessors: {
        heading: {
          attribute: {},
          set: function(value){
            if (setHeader(this)) this.xtag.header.innerHTML = value;
          }
        },
        subheading: {
          attribute: {},
          set: function(value){
            if (setHeader(this)) this.xtag.header.setAttribute('subheading', value);
          }
        }
      }
    });
  
  })();
  