Java tutorial
import javax.swing.JFrame; import javax.swing.event.AncestorEvent; import javax.swing.event.AncestorListener; public class Main { public static void main(String args[]) { JFrame f = new JFrame("Ancestor Sampler"); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); AncestorListener ancestorListener = new AncestorListener() { public void ancestorAdded(AncestorEvent ancestorEvent) { System.out.println("Added"); } public void ancestorMoved(AncestorEvent ancestorEvent) { System.out.println("Moved"); } public void ancestorRemoved(AncestorEvent ancestorEvent) { System.out.println("Removed"); } }; f.getRootPane().addAncestorListener(ancestorListener); f.getRootPane().setVisible(false); f.getRootPane().setVisible(true); f.setSize(300, 200); f.setVisible(true); } }