Test implementation of FB Auth in C# (not working properly!)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Shapes;
using System.Text.RegularExpressions;

namespace _008_FacebookLogin
{
    /// <summary>
    /// Interaction logic for FBLoginWindow.xaml
    /// </summary>
    public partial class FBLoginWindow : Window
    {
        public FBLoginWindow()
        {
            InitializeComponent();
        }

        /// <summary>
        /// Property to indicate if authentication with facebook was a success
        /// </summary>
        public bool AuthenticatedSuccessfully
        {
            get
            {
                // Cast to a browser control to get at the current source
                if (uiFrameLogin.Content.GetType() == typeof(WebBrowser))
                {
                    WebBrowser webBrowser = (WebBrowser)uiFrameLogin.Content;
                    if (webBrowser.Source != null && webBrowser.Source.ToString().Contains("&error"))
                        return false; // look for an error
                    else
                        if (
                            webBrowser.Source != null &&
                            webBrowser.Source.AbsolutePath.Contains("login_success")
                           )
                        {
                            string temp;
                            temp = Regex.Replace(webBrowser.Source.Fragment, "^.*access_token=", "");
                            Properties.Settings.Default.FBAccessToken = System.Text.RegularExpressions.Regex.Replace(temp, "&.*", "");

                            temp = Regex.Replace(webBrowser.Source.Fragment, "^.*access_token=.*&", "");
                            Properties.Settings.Default.FBExpiresIn = System.Text.RegularExpressions.Regex.Replace(temp, "expires_in=", "");

                            return true; // if its at this page, we've auth'd successfully
                        }
                }

                return false; // cant find the success page, cant indicate a successful auth - no return false.
            }
        }


        /// <summary>
        /// Load the wait page while we load the login page "in the background"
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Window_Loaded(object sender, RoutedEventArgs e)
        {
            StringBuilder authReqUri = new StringBuilder("https://www.facebook.com/dialog/oauth?client_id=");
            authReqUri.Append(Properties.Settings.Default.FBAppID);
            authReqUri.Append(   "&redirect_uri=https://www.facebook.com/connect/login_success.html&scope=");
            authReqUri.Append(Properties.Settings.Default.FBScope);
            authReqUri.Append("&response_type=token");
            Properties.Settings.Default.FBReqString = authReqUri.ToString();
            return;
        }

        /// <summary>
        /// When the window closes, check the login has been successful, if not, by jove, let the user know!
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
            if (!AuthenticatedSuccessfully)
            {
                if (MessageBox.Show("You have not logged in properly, continue to exit?", "Error", MessageBoxButton.YesNo, MessageBoxImage.Exclamation) == MessageBoxResult.No)
                {
                    e.Cancel = true;
                }
            }
        }

    }
}