function facebook_ready(callback)
{
  if (window['facebook_loaded'] == true) callback();
  else window.setTimeout(function() { facebook_ready(callback); }, 250);
}
function facebook_promptPermission(permission, callback) { facebook_ready(function() { FB.Facebook.apiClient.users_hasAppPermission(permission, function(result) { if (result == 0) FB.Connect.showPermissionDialog(permission, callback); else callback(true); }); }); }