Como criar uma janela(JFrame) "intocável"?

import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;


public class TesteOverlay {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		new TesteOverlay().teste();
	}

	private void teste() {
		JFrame frame = new JFrame("Overlay");
		JButton botao = new JButton("Teste");
		frame.add(botao);
		frame.setSize(640, 480);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setVisible(true);
		frame.setGlassPane(new Overlay());
		botao.setAction(new ShowOverlay());
	}

	class ShowOverlay extends AbstractAction {
		private static final long serialVersionUID = 1817243571776498418L;

		public ShowOverlay() {
			putValue(NAME, "Teste");
		}
		
		@Override
		public void actionPerformed(ActionEvent e) {
			JButton botao = (JButton) e.getSource();
			JFrame theFrame = (JFrame) botao.getTopLevelAncestor();
			Overlay overlay = (Overlay) theFrame.getGlassPane();
			overlay.mostra("Apertou", 1);
		}
		
	}
	
	class Overlay extends JComponent implements Runnable {
		private static final long serialVersionUID = 8906385904245788553L;

		String texto = "";
		Long fim = 0L;
		Thread thread;
		
		public void mostra(String string, int i) {
			texto = string;
			synchronized (fim) {
				fim = System.currentTimeMillis() + (i * 1000);
			}
			setVisible(true);
			if (thread == null) {
				thread = new Thread(this);
				thread.start();
			}
		}
		
	    public void paint(Graphics g) {
	        g.setColor(Color.red);
	        g.drawString(texto, 10, 20);
	    }

		@Override
		public void run() {
			synchronized (fim) {
				while(System.currentTimeMillis() < fim) {
					Thread.yield();
				}
				setVisible(false);
				thread = null;
			}
		}
	}
}