Code below illustrates that the headless implementation of Toolkit ignores addAWTEventListener method call:
========================== Test3.java ================================
import java.awt.*;
import java.awt.event.*;

public class Test3 {

    public static void main( String argv[] ) {
        Test3 t = new Test3();
        t.go();
    }
    public void go() {
        Toolkit t = Toolkit.getDefaultToolkit();
        AWTEventListener ael = new MyAWTEventListener();
        t.addAWTEventListener(ael, AWTEvent.CONTAINER_EVENT_MASK);
        AWTEventListener[] outList =
            t.getAWTEventListeners();
    
        if (outList.length == 0) {
            System.out.println("An empty array returned unexpectedly");
        }
        System.exit(0);
    }
    class MyAWTEventListener implements AWTEventListener {
        public void eventDispatched(AWTEvent event) {}
    }
}
================== output ================================
--> java -version
java version "1.6.0-ea"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.6.0-ea-b31)
Java HotSpot(TM) Client VM (build 1.6.0-ea-b31, mixed mode)

--> java -Djava.awt.headless=true Test3
An empty array returned unexpectedly

###@###.### 2005-04-26 09:47:58 GMT