JavaFX创建一个对话框

Question

Main.class

package application;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.scene.Parent;
import javafx.scene.Scene;

public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            // BorderPane root = new BorderPane();
            Parent root = FXMLLoader.load(getClass().getResource("/application/MainWindow.fxml"));
            Scene scene = new Scene(root, 400, 400);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            primaryStage.setScene(scene);
            primaryStage.show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}

package application;

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.text.Text;
import javafx.stage.Stage;
import javafx.stage.StageStyle;

public class MainWindowController {

    public void buttonAction(ActionEvent event) {

        Stage dialog = new Stage();
        dialog.initStyle(StageStyle.TRANSPARENT);
        Scene scene = new Scene(new Group(new Text(260, 260, "Hello World!")));
        // its Just for checking I want add .fxml here how can I do?
        dialog.setScene(scene);
        dialog.show();
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane prefHeight="400.0" prefWidth="400.0" xmlns="http://javafx.com/javafx/8.0.65" xmlns:fx="http://javafx.com/fxml/1" fx:controller="application.MainWindowController">
   <children>
      <Button fx:id="bt1" layoutX="154.0" layoutY="188.0" mnemonicParsing="false" onAction="#buttonAction" text="Login" />
   </children>
</AnchorPane>

当我点击登录按钮时，会打开一个包含表单的对话框。 我是怎么做到的我的对话框只包含标题栏上的关闭按钮，当我的对话框打开时，我没有在我的主MAinWindow中执行任何操作。它只显示没有焦点。我怎样才能做到这一点？