import javax.swing.*;  
import java.awt.*;  
import java.awt.event.*;  
public class TestDialog {  
      public static void main(String args[])  
    {  
          Window frame = null;
       JDialog dialog = new JDialog( frame, null, Dialog.ModalityType.DOCUMENT_MODAL ); 
                dialog.getRootPane().putClientProperty( "apple.awt.documentModalSheet", Boolean.TRUE ); 
                dialog.add( new JLabel( "Hello world!" ) ); 
                dialog.pack(); 
                dialog.setVisible( true );
    }  
}