<zk>
	<window apply="test.ComboTestComposer">
		<combobox model="@{ctl.list}" 
				selectedItem="@{ctl.selItem}" 
			    forward="onChange=onSelectItem" width="300px" readonly="true">
		<comboitem self="@{each=item}" value="@{item}" label="@{item.name}"></comboitem>
	</combobox>
	</window>
</zk>

package test;

import java.util.ArrayList;
import java.util.List;

import org.zkoss.zk.ui.Component;
import org.zkoss.zk.ui.event.Event;
import org.zkoss.zk.ui.util.GenericForwardComposer;
import org.zkoss.zkplus.databind.AnnotateDataBinder;

public class ComboTestComposer extends GenericForwardComposer {
	private AnnotateDataBinder binder;
	private Item selItem;
	private List<Item> list;

	@Override
	public void doAfterCompose(Component comp) throws Exception {
		super.doAfterCompose(comp);
		binder = new AnnotateDataBinder(comp);
		comp.setAttribute("ctl", this);

		list = new ArrayList<Item>();
		list.add(new Item("Item 1"));
		list.add(new Item("Item 2"));
		list.add(new Item("Item 3"));
		binder.loadAll();
	}

	public void onSelectItem(Event event) {
		binder.loadAll();
	}

	public List<Item> getList() {
		return list;
	}

	public void setList(List<Item> list) {
		this.list = list;
	}

	public Item getSelItem() {
		return selItem;
	}

	public void setSelItem(Item selItem) {
		this.selItem = selItem;
	}
	
	public static class Item {
		private String name;

		public Item(String name) {
			super();
			this.name = name;
		}

		public String getName() {
			return name;
		}

		public void setName(String name) {
			this.name = name;
		}
	}

}