private void btnLogin_Click(object sender, RoutedEventArgs e) { WebserviceObject wsObj = WebserviceCalls.CheckLogin(tbUsername.Text, tbPassword.Password); if (wsObj.Success) { MainWindow mainWindow = new MainWindow((User)wsObj.Response); mainWindow.Show(); this.Close(); // Go to next window } else { MessageBox.Show(wsObj.Response.ToString()); } }