facebook-csharp-sdk/facebook-winclient-sdk — pull request #31 by RCGame (2013-08-18 07:40:22+00:00)
Title: Request dialog is now working. Prepared for other types of dialog.

I have also provided this sample in BasicApp using a new pivot item "request".

var result = await FacebookWebDialog.PresentRequestDialogAsync("My Title", "My Message", null);

When you scroll to request, it starts popup RequestDialog asynchronously.
You also have to pull my small change in facebook-csharp-sdk to make this work.