ZK 5.0.1-FL-2010-02-12 Listbox live data creating nodes for all the rows

<?page title="Test" contentType="text/html;charset=UTF-8"?>
<zk>
	<zscript>
	ListModel strset = new com.bodyfs.ui.FakeListModel(10000);
</zscript>
	<listbox id="list" width="200px" rows="10" model="${strset}">
		<listhead>
			<listheader label="Load on Demend" sort="auto" />
		</listhead>
	</listbox>
</zk>

package com.bodyfs.ui;

import java.util.Comparator;

import org.zkoss.zul.AbstractListModel;
import org.zkoss.zul.ListModelExt;
import org.zkoss.zul.event.ListDataEvent;

public class FakeListModel extends AbstractListModel implements ListModelExt {

	private static final long serialVersionUID = 4143517731003447818L;
	private int _size;
	private boolean _asc = true;

	public FakeListModel() {
		this(10000);
	}

	public FakeListModel(int size) {
		_size = size;
	}

	// ListModelExt
	@SuppressWarnings("unchecked")
	public void sort(Comparator cmpr, boolean asc) {
		// System.out.println("==================SORT DATA================");
		_asc = asc;
		invalidate();
	}

	public void invalidate() {
		fireEvent(ListDataEvent.CONTENTS_CHANGED, -1, -1);
	}

	// AbstractListModel
	public Object getElementAt(int v) {
		String value = "Option " + (_asc ? v : _size - v - 1);
		// System.out.println(value);
		return value;
	}

	// AbstractListModel
	public int getSize() {
		return _size;
	}

	// AbstractListModel
	public void setSize(int size) {
		_size = size;
	}

}