void BeginLoadingInitialUrl()
        {
            authenticator.GetInitialUrlAsync().ContinueWith(t =>
            {
                if (t.IsFaulted)
                {
                    keepTryingAfterError = false;
                    authenticator.OnError(t.Exception);
                }
                else
                {
                    // Delete cookies so we can work with multiple accounts
                    if (this.authenticator.ClearCookiesBeforeLogin)
                    {
                        WebAuthenticator.ClearCookies();
                    }

                    //
                    // Begin displaying the page
                    //
                    Uri uri = t.Result;
                    LoadInitialUrl(uri);
                }
            }, TaskScheduler.FromCurrentSynchronizationContext());
        }
        protected override async void OnNavigatedTo(NavigationEventArgs e)
        {
            authenticator = (OAuth2Authenticator)e.Parameter;

            url_initial = this.authenticator.GetInitialUrlAsync().Result;
            this.browser.Navigate(url_initial);

            System.Diagnostics.Debug.WriteLine("OnNavigatedTo authenticator = " + authenticator.Title);

            authenticator.Completed += auth_Completed;
            authenticator.Error     += auth_Error;

            url_initial = await authenticator.GetInitialUrlAsync();

            base.OnNavigatedTo(e);

            return;
        }