facebook fb.ui apprequests with skip option?

I am trying to use the Dialog for "Invite Friends" via Javascript SDK:

function sendRequestToManyRecipients() {
        FB.ui({method: 'apprequests',
          message: 'My Great Request',
        }, requestCallback);
} 

from https://developers.facebook.com/docs/reference/dialogs/requests This wo开发者_如何学Gorks fine for me in case the user selects his friends and submits. My question is how can I also add "Skip" button through this function and if I can also catch the event of clicking "Skip"...any suggestions are highly appreciated! Thanks!

There is an ajax request fired when apprequests is called. In the callback you will find a response.to array in case if the user selects a friend. If the user does not select it is blank. A blank array in response.to is only when the user skips the dialog box.