title: Polymer default page with data binding
body: <p>I have an index page that has its template set to dom-bind and have data binding on the page as well as the paper-menu selection/button. In my script I have this:</p>
  
  <pre><code>var app = document.querySelector('#app');
  
  app.selected = 0;
  </code></pre>
  
  <p>from what I understand that should set the page to index 0, but it doesn't. My main content area is blank, and if I select the menu item it changes happily. Just not on load. Something I am missing?</p>