Run this app on OS-X with latest 8u40 build and it core dumps.

This is not a regression I've tested 8u05, 8u20 and they core dump in the same way. Still I think this is a major problem because the application dies

package application;

import javafx.application.Application;
import javafx.beans.Observable;
import javafx.event.ActionEvent;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;


public class Main extends Application {
@Override
public void start(Stage primaryStage) {
try {
BorderPane root = new BorderPane();
Button b = new Button("Open");
b.setOnAction((e) -> open(primaryStage));
root.setCenter(b);
Scene scene = new Scene(root,400,400);
primaryStage.setScene(scene);
primaryStage.show();
} catch(Exception e) {
e.printStackTrace();
}
}

private void open(Stage primaryStage) {
Stage utility = new Stage(StageStyle.UNDECORATED);
BorderPane p = new BorderPane(new Button("Hello Util"));
utility.setScene(new Scene(p,300,200));
utility.show();
utility.requestFocus();
utility.focusedProperty().addListener(o -> {
if( ! utility.isFocused() ) {
utility.close();
}
});
}

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