/// <summary>
        /// Occurs on click on a button to refresh access token.
        /// </summary>
        /// <param name="sender">The event sender.</param>
        /// <param name="e">The event arguments.</param>
        private void RefreshTokenButtonClick(object sender, RoutedEventArgs e)
        {
            var authorization = new DriveAuthorization(new DriveAuthData());
            var context       = DataContext as DriveContext;

            Debug.Assert(context != null, "context != null");
            Task.Factory.StartNew(() =>
            {
                try
                {
                    context.AccessToken = authorization.RefreshToken(context.AccessToken).Data;
                }
                catch (Exception exception)
                {
                    Dispatcher.BeginInvoke(new Action <Exception>(ShowErrorMessage), exception);
                }
            });
        }
 public DriveConnectWindow()
 {
     InitializeComponent();
     Authorization = new DriveAuthorization(new DriveAuthData());
 }