title: How to determine if a user allows my app to post to facebook
body: <p>I have a rails app that uses omniauth to enable user registration through facebook.  My facebook app requests permission from the user to make posts to facebook on the user's behalf.  My question is, is there a way for me to determine whether a user "skips" granting that permission during the authentication process (it doesn't seem possible for the user to actually reject the granting of this permission . . . they can only skip it)?  I can't see anything in the request.env that is returned by the facebook callback.  </p>
  
  <p>Just as an aside, there seems to be all sorts of issues with fb-graph and granting posting permission.  For example, even if a user "skips" granting this permission, when the user looks at his fb authorized apps, my app shows up indicating that the user has granted this permission even though fb blocks my app from making fb posts.  Also, it seems impossible for a user to subsequently change his mind about allowing my app to post to fb: you can't even edit the application on fb to actually grant the permission.</p>
  
  <p>Am I missing something about fb-graph???</p>