private void StartLogin()
        {
            // Disable the button
            this.LoginButton.IsEnabled = false;

            // Init ModelProvider
            ModelProvider mp = ModelProvider.Instance;

            mp.Clean();
            mp.UserId   = UserNameTextbox.Text;
            mp.Password = PasswordTextbox.Password;
            // TODO: remove below in released version
            //mp.UserId = @"*****@*****.**";
            //mp.Password = @"beelun";
            this.NavigationService.Navigate(new Uri("/LoadingProgress", UriKind.Relative));
        }