title: How to do FB.ui({ method: 'auth.login' ...) with display: 'iframe' instead of 'popup'?
body: <p>I'm working on a login for a simple Facebook app. I'm able to use the JavaScript SDK to successfully present a login / extended permissions dialog in a popup window with either FB.login or the following code:</p>
  
  <pre><code>FB.ui({ method: 'auth.login',
      perms: 'read_stream,publish_stream',
      display: 'popup' },
      function (rsp) {
          fg_log('on login');                             
          if(rsp.session) { 
              if(rsp.perms) {
                  fg_log('PERMS: ',rsp.perms);
              } else {
                  fg_log('Hmm. No permissions');
              }
          } else {
              fg_log('Hmm. No login');
          }
      }
  );
  </code></pre>
  
  <p>The problem is... I don't like popup windows much. From a UI standpoint, I think they feel off, like they don't belong to the rest of the app. And getting them to show up via JavaScript also require an extra click from the user for no reason -- in order to get around popup blockers, the user has to click on something like a login button (largely pointless, given that by the time the app knows it needs to display a login button, it already knows the user needs to log in and may as well just present the permissions dialog). </p>
  
  <p>So, I thought, why not an iframe instead? No issues with popup blockers, embedded nicely in the page, and Facebook seems to love 'em.</p>
  
  <p>A little digging in the recent (2.1.2) JavaScript SDK source and various other posts on the Facebook developers forum seems to indicate one can pass "display: 'iframe'" as part of the options to FB.ui. </p>
  
  <p>But when I try it, though the iframe does come up, instead of getting the permissions dialog, I get:</p>
  
  <blockquote>
    <p>"An error occurred with . Please try again later."</p>
  </blockquote>
  
  <p>(Note: trying again later produces the same results.)</p>
  
  <p>is there a trick to get this to work, or is it forbidden for some reason?</p>