Refresh Listbox Model after button click

<?xml version="1.0" encoding="UTF-8"?>
<?init class="org.zkoss.zkplus.databind.AnnotateDataBinderInit" ?>
<?page title="Data Binding Example" id="data_bind_example" ?>
<window id="testWin" xmlns="http://www.zkoss.org/2005/zul"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:a="http://www.zkoss.org/2005/zk/annotation"
	xsi:schemaLocation="http://www.zkoss.org/2005/zul http://www.zkoss.org/2005/zul/zul.xsd"
	use="com.test.DataBindExampleWindow"
	width="95%" position="center" sclass="body1">
	<hbox>
		<listbox model="@{testWin.people, load-when='first_name.onChange, last_name.onChange, create_person_btn.onClick', access='load'}"
			selectedItem="@{testWin.selectedPerson, load-when='create_person_btn.onClick', access='both'}"
			itemRenderer="com.test.PersonListitemRenderer"
			rows="10">
		</listbox>
		<vbox>
			<hbox>
				First Name:
				<textbox id="first_name" value="@{testWin.selectedPerson.firstName}" />
			</hbox>
			<hbox>
				Last Name:
				<textbox id="last_name" value="@{testWin.selectedPerson.lastName}" />
			</hbox>
			<hbox>
				Date of Birth:
				<datebox value="@{testWin.selectedPerson.dateOfBirth}" format="MM/dd/yyyy" />
			</hbox>
		</vbox>
	</hbox>
	<button id="create_person_btn" onClick="testWin.createPerson()" label="Create" />
</window>

package com.test;

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

import org.zkoss.zul.ListModel;
import org.zkoss.zul.SimpleListModel;
import org.zkoss.zul.Window;

public class DataBindExampleWindow extends Window {
	private static final long serialVersionUID = 2255149977062345551L;

	private List<Person> people = new ArrayList<Person>();
	private Person selectedPerson = null;

	public DataBindExampleWindow() {
		super();
		init();
	}
	public DataBindExampleWindow(String title, String border, boolean closable) {
		super(title, border, closable);
		init();
	}
	public ListModel getPersonListModel() {
		return new SimpleListModel(people);
	}
	private void init() {
		Calendar bday = Calendar.getInstance();
		bday.add(Calendar.YEAR, -1 * (int) Math.round(Math.random() * 70));
		bday.add(Calendar.MONTH, (int) Math.round(Math.random() * 12));
		bday.add(Calendar.DATE, (int) Math.round(Math.random() * 31));
		people.add(new Person("Barack", "Obama", bday.getTime()));

		bday = Calendar.getInstance();
		bday.add(Calendar.YEAR, -1 * (int) Math.round(Math.random() * 70));
		bday.add(Calendar.MONTH, (int) Math.round(Math.random() * 12));
		bday.add(Calendar.DATE, (int) Math.round(Math.random() * 31));
		people.add(new Person("Joe", "Biden", bday.getTime()));

		bday = Calendar.getInstance();
		bday.add(Calendar.YEAR, -1 * (int) Math.round(Math.random() * 70));
		bday.add(Calendar.MONTH, (int) Math.round(Math.random() * 12));
		bday.add(Calendar.DATE, (int) Math.round(Math.random() * 31));
		people.add(new Person("John", "McCain", bday.getTime()));

		bday = Calendar.getInstance();
		bday.add(Calendar.YEAR, -1 * (int) Math.round(Math.random() * 70));
		bday.add(Calendar.MONTH, (int) Math.round(Math.random() * 12));
		bday.add(Calendar.DATE, (int) Math.round(Math.random() * 31));
		people.add(new Person("Sarah", "Palin", bday.getTime()));

		bday = Calendar.getInstance();
		bday.add(Calendar.YEAR, -1 * (int) Math.round(Math.random() * 70));
		bday.add(Calendar.MONTH, (int) Math.round(Math.random() * 12));
		bday.add(Calendar.DATE, (int) Math.round(Math.random() * 31));
		people.add(new Person("George", "Bush", bday.getTime()));
	}
	
	public void createPerson() {
		final Person person = new Person(null, null, null);
		people.add(person);
		setSelectedPerson(person);
	}
	
	/**
	 * @return the selectedPerson
	 */
	public Person getSelectedPerson() {
		return selectedPerson;
	}
	/**
	 * @param selectedPerson the selectedPerson to set
	 */
	public void setSelectedPerson(Person selectedPerson) {
		this.selectedPerson = selectedPerson;
	}
	/**
	 * @return the people
	 */
	public List<Person> getPeople() {
		return people;
	}
	/**
	 * @param people the people to set
	 */
	public void setPeople(List<Person> people) {
		this.people = people;
	}
}

package com.test;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;

public class Person {
	private String firstName = null;
	private String lastName = null;
	private Date dateOfBirth = null;
	private String formattedDateOfBirth = null;

	public Person() {
		super();
	}
	public Person(String firstName, String lastName) {
		super();
		this.firstName = firstName;
		this.lastName = lastName;
	}
	public Person(String firstName, String lastName, Date dateOfBirth) {
		super();
		setFirstName(firstName);
		setLastName(lastName);
		setDateOfBirth(dateOfBirth);
	}
	public String getFullname() {
		final StringBuffer fullName = new StringBuffer();
		if (firstName != null) {
			fullName.append(firstName).append(" ");
		}
		if (lastName != null) {
			fullName.append(lastName);
		}
		return fullName.toString().trim();
	}
	public Date getDateOfBirth() {
		return dateOfBirth;
	}
	public void setDateOfBirth(Date dateOfBirth) {
		this.dateOfBirth = dateOfBirth;
		
		if (dateOfBirth == null) {
			setFormattedDateOfBirth("");
		} else {
			final DateFormat formatter = new SimpleDateFormat("MMM d, yyyy");
			setFormattedDateOfBirth(formatter.format(dateOfBirth));
		}
	}
	public String getFirstName() {
		return firstName;
	}
	public void setFirstName(String firstName) {
		this.firstName = firstName;
	}
	public String getLastName() {
		return lastName;
	}
	public void setLastName(String lastName) {
		this.lastName = lastName;
	}
	public String getFormattedDateOfBirth() {
		return formattedDateOfBirth;
	}
	public void setFormattedDateOfBirth(String formattedDateOfBirth) {
		this.formattedDateOfBirth = formattedDateOfBirth;
	}
}

package com.test;

import org.zkoss.zul.Listcell;
import org.zkoss.zul.Listitem;
import org.zkoss.zul.ListitemRenderer;

public class PersonListitemRenderer implements ListitemRenderer {
	public void render(Listitem item, Object data) throws Exception {
		if (data instanceof Person) {
			final Person p = (Person) data;
			item.setValue(p);
			
			final Listcell cell = new Listcell(p.getFullname());
			// How to bind the label of the cell to my person's fullname?
			item.appendChild(cell);
		}
	}
}