Nonsense Gui

import javafx.animation.AnimationTimer;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Alert;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.control.Button;
import javafx.scene.control.ButtonType;
import javafx.scene.control.Label;
import javafx.scene.input.MouseDragEvent;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class Amazing extends Application{
    public static void main(String[] args) {
        launch();
    }

    private Stage stage;
    private Scene scene;
    private Pane  pane;
    @Override
    public void start(Stage primaryStage) throws Exception {
        (stage = primaryStage).setScene(scene = new Scene(pane = new Pane(), 300, 300));
        primaryStage.setResizable(false);
        populate();

        primaryStage.show();
    }

    private void populate() {
        Label label = new Label("Java?");
        Button yes = new Button("Yes"), no = new Button("No");
        yes.setOnAction((e)->{notify("K thnkx");});
        GridPane gp = new GridPane();
        pane.getChildren().add(gp);
        gp.translateXProperty().bind(pane.widthProperty().divide(2).subtract(gp.widthProperty().divide(2)));
        gp.translateYProperty().bind(pane.heightProperty().divide(2).subtract(gp.heightProperty()).divide(2));
        gp.add(label, 0, 0, 2, 1);
        gp.addRow(1, yes, no);
        gp.setHgap(20);
        gp.setVgap(20);
        AnimationTimer at = new AnimationTimer() {
            long nextRot = 0;
            @Override
            public void handle(long _unusedNanosecondTimer) {
                if(nextRot <= System.currentTimeMillis()) {
                    pane.setRotate(pane.getRotate()+3);
                    nextRot = System.currentTimeMillis()+10;
                }
            }
        };

        no.setOnMouseEntered((e)->{
            at.start();
        });
        no.setOnMouseExited((e)->{
            at.stop();
        });


        no.setOnAction((e)->{
            gp.getChildren().removeAll(yes,no);
            gp.addRow(1, no, yes);
            attemptToClickNo = true;
            yes.fire();
        });
        stage.setOnCloseRequest((e)->{
            e.consume();
            notify("The real exit button is \"Yes\"");
        });
        yes.setOnAction((e)->{
            notify("Thank you for choosing yes." + (attemptToClickNo? "\n (Buttons swapped)":""));
            stage.close();
        });
    }
    private static volatile boolean attemptToClickNo = false;
    private void notify(String msg) {
        Alert alert = new Alert(AlertType.INFORMATION, msg, ButtonType.OK);
        alert.showAndWait();
    }

}