NestedLibGDXApplication.java

import com.badlogic.gdx.ApplicationAdapter;
import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.backends.lwjgl.LwjglApplicationConfiguration;
import com.badlogic.gdx.backends.lwjgl.LwjglCanvas;
import java.awt.Canvas;
import javax.swing.JFrame;
import javax.swing.JPanel;

public final class SwingWindow extends JFrame {

    public SwingWindow() {

        LwjglApplicationConfiguration cfg = new LwjglApplicationConfiguration();

        cfg.width = 800;
        cfg.height = 60;

        super.setSize(cfg.width, cfg.height);
        super.setTitle(cfg.title);

        JPanel panel = new JPanel();
        Canvas canvas = new LwjglCanvas(new ApplicationAdapter() {}, cfg).getCanvas();
        canvas.setBounds(0, 0, super.getWidth(), super.getHeight());

        panel.add(canvas);

        super.add(panel);

        super.setLocationRelativeTo(null);
        super.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
        super.setUndecorated(true);
        super.setLocationRelativeTo(null);
    }

    @Override
    public void dispose() {
        super.dispose();
        Gdx.app.exit();
    }
}