private void OnFrameNavigated(object sender, NavigationEventArgs e)
        {
            if (e.Content == _frameContentWhenOpened)
            {
                CloseLoginPage();
            }
            else if (_facebookLoginPage == null)
            {
                _facebookLoginPage = e.Content as IFacebookLoginPage;
                if (_facebookLoginPage != null)
                {
                    _facebookLoginPage.AppId = AppId;
                    _facebookLoginPage.ExtendedPermissions = ExtendedPermissions;
                    _facebookLoginPage.AccessToken         = AccessToken;

                    if (e.Uri.ToString().Contains("action=logout"))
                    {
                        _facebookLoginPage.Logout();
                    }
                    else
                    {
                        _facebookLoginPage.ShowDialog();
                    }
                }
            }
        }
        private void OnFrameNavigated(object sender, NavigationEventArgs e)
        {
            if (e.Content == _frameContentWhenOpened) {
                CloseLoginPage();
            }
            else if (_facebookLoginPage == null) {
                _facebookLoginPage = e.Content as IFacebookLoginPage;
                if (_facebookLoginPage != null) {
                    _facebookLoginPage.AppId = AppId;
                    _facebookLoginPage.ExtendedPermissions = ExtendedPermissions;
                    _facebookLoginPage.AccessToken = AccessToken;

                    if (e.Uri.ToString().Contains("action=logout")) {
                        _facebookLoginPage.Logout();
                    }
                    else {
                        _facebookLoginPage.ShowDialog();
                    }
                }
            }
        }