public class MySelectorComposer extends SelectorComposer<Component> {
	
	private static final long serialVersionUID = -768423404327342087L;

	@Listen("onClick = #btn")
	public void testEvent(){
		System.out.println(" SelectorComposer click");
		Messagebox.show(" SelectorComposer click");

	}
}

<zk>
<window id="win" title="test" border="normal" apply="test.MySelectorComposer">
    <button label="test" id="btn" />
</window>
</zk>