I used to be able to create a WebBrowser control, navigate to the login URL (e.g. \"http://www.facebook.com/dialog/oauth/?response_type=token&display=popup&scope=user_ab
I'm pretty sure this is http://facebooksdk.codeplex.com/discussions/261528, an interaction between a change in Facebook behavior and an issue with the WPF WebBrowser control. I was able to work around my issue by switching to WinForms. The link discusses an alternate approach which stays with WPF but adds a call to FacebookOAuthClient.ExchangeCodeForAccessToken().