Run code, press button:


import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Ellipse;
import javafx.scene.text.Text;
import javafx.stage.Popup;
import javafx.stage.Stage;

public class MenuButtonApp extends Application {

    private Popup p1;
    private Button parentButton;

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

    @Override
    public void start(final Stage stage) throws Exception {
        p1 = new Popup();

        parentButton = new Button("Parent");
        parentButton.setOnAction(new EventHandler<ActionEvent>() {

            @Override
            public void handle(ActionEvent t) {
                p1.show(p1, 100, 100);
            }
        });

        p1.setAutoFix(true);
        p1.setAutoHide(false);

        StackPane stack = new StackPane();
        Ellipse ellipse = new Ellipse(70.0F, 50.0F);
        ellipse.setFill(Color.AQUAMARINE);
        stack.getChildren().clear();
        stack.getChildren().addAll(ellipse, new Text("Popup!!"));
        p1.getContent().clear();
        p1.getContent().addAll(stack);

        Scene scene = new Scene(new Group(), 300, 300);
        VBox vbox = new VBox(5.0F);
        vbox.getChildren().clear();
        vbox.getChildren().addAll(parentButton);
        ((Group) scene.getRoot()).getChildren().clear();
        ((Group) scene.getRoot()).getChildren().addAll(vbox);
        stage.setScene(scene);
        stage.show();
    }
}