title: jQuery, Shadowbox + Facebook JS SDK: access to property ownerDocument denied
body: <p>In a custom CMS, the website's editors may enable a sidebar-box in order to display one of the latest Facebook-Fanpage-Posts and it's associated comments.</p>
  
  <p>For selecting the appropiate Post, a form is opened via Shadowbox = as iFrame.</p>
  
  <p>Within this iFrame</p>
  
  <ul>
  <li>FB Javascript SDK is initialized</li>
  <li>Fanpage-Posts are fetched (with Access-Token)</li>
  <li>A Dropdown is being populated with the Posts (first 20 chars of each post)</li>
  </ul>
  
  <p>When an editor selects one of the posts excerpts in the dropdown, two further input fields (disabled for user-input) are populated with the post-id / the full post message.</p>
  
  <p>On hitting a SAVE button, those two values (id + message that have been written into the disabled input fields before) are supposed to be saved, and the shadowbox shall close.</p>
  
  <p>Everything works fine, except the saving part in Firefox:
  Error: Permission denied to access property 'ownerDocument' in jquery-1.6.4.min.js line 5151.</p>
  
  <p>The code evoking the error (in accordance with the error log):</p>
  
  <pre><code>    Sizzle.isXML = function( elem ) {
      // documentElement is verified for cases where it doesn't yet exist
      // (such as loading iframes in IE - #4833) 
      var documentElement = (elem ? elem.ownerDocument || elem : 0).documentElement;
  
  return documentElement ? documentElement.nodeName !== "HTML" : false;
  </code></pre>
  
  <p>};</p>
  
  <p>The main CMS page and the iFrame contents are both served from the same domain, I think I may rule out Cross-Domain-Errors?</p>