package demo;
public class BookVM {
	
	List<Item> items;
	String label2;
	
	public class Item {
		String name;

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

		public String getName() {
			return name;
		}
	}
	
	public List<Item> getItems() {
		items = (ListModelList<Item>) Sessions.getCurrent().getAttribute("items");
		if (items == null) {
			Sessions.getCurrent().setAttribute("items", items = new ListModelList<Item>());
			items.add(new Item("A"));
		}
		return items;
	}
	
	@GlobalCommand
	public void doButton(@BindingParam("item") Item item) {
		System.out.println("vm1:" + item.getName());
	}
}

package demo;
public class BookVM2 {

	List<CheckItem> checkItems;
	
	public class CheckItem {
		String name;

		public CheckItem(String name) {
			this.name = name;
		}

		public String getName() {
			return name;
		}
	}
	
	public List<CheckItem> getCheckItems() {
		checkItems = (ListModelList<CheckItem>) Sessions.getCurrent().getAttribute("checkItems");
		if (checkItems == null) {
			Sessions.getCurrent().setAttribute("checkItems", checkItems = new ListModelList<CheckItem>());
			checkItems.add(new CheckItem("AAA"));
		}
		return checkItems;
	}
	
	@GlobalCommand @NotifyChange("checkItems")
	public void doButton(@BindingParam("item") Item item) {
		System.out.println("vm2:" + item.getName());
		CheckItem i = new CheckItem(item.getName());
		checkItems.add(i);
	}
}

<zk>
	<window border="normal" width="100%" height="100%">
		<borderlayout>
			<center>
				<div apply="org.zkoss.bind.BindComposer" 
					viewModel="@id('vm1') @init('demo.BookVM')" 
					binder="@init(queueScope='session')">
					<grid model="@load(vm1.items)">
						<columns sizable="true">
							<column />
							<column />
							<column />
						</columns>
						<template name="model" var="item">
							<row>
								<cell><label value="@bind(item.name)" /></cell>
								<cell><label value="aaaa" /></cell>
								<cell>
									<button label="click" onClick="@global-command('doButton', item=item)" />
								</cell>
							</row>
						</template>
					</grid>
				</div>
			</center>
			<east size="35%">
				<div apply="org.zkoss.bind.BindComposer" 
					viewModel="@id('vm2') @init('demo.BookVM2')" 
					binder="@init(queueScope='session')">
					<listbox model="@load(vm2.checkItems)">
						<listhead sizable="true">
							<listheader width="15%" />
						</listhead>
						<template name="model" var="citem">
							<listitem>
								<listcell label="@bind(citem.name)" />
							</listitem>
						</template>
					</listbox>
				</div>
			</east>
		</borderlayout>
	</window>
</zk>

java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at org.zkoss.bind.impl.ParamCall.call(ParamCall.java:108)
	at org.zkoss.bind.impl.BinderImpl.doGlobalCommandExecute(BinderImpl.java:1314)
	at org.zkoss.bind.impl.BinderImpl.doGlobalCommand(BinderImpl.java:1291)
	at org.zkoss.bind.impl.BinderImpl.access$2(BinderImpl.java:1281)
	at org.zkoss.bind.impl.BinderImpl$QueueListener.onEvent(BinderImpl.java:235)
	at org.zkoss.zk.ui.event.impl.DesktopEventQueue$QueueListener.onEvent(DesktopEventQueue.java:145)
	at org.zkoss.zk.ui.AbstractComponent.onEvent(AbstractComponent.java:2741)
	at org.zkoss.zk.ui.AbstractComponent.service(AbstractComponent.java:2712)
	at org.zkoss.zk.ui.AbstractComponent.service(AbstractComponent.java:2653)
	at org.zkoss.zk.ui.impl.EventProcessor.process(EventProcessor.java:136)
	at org.zkoss.zk.ui.impl.UiEngineImpl.processEvent(UiEngineImpl.java:1699)
	at org.zkoss.zk.ui.impl.UiEngineImpl.process(UiEngineImpl.java:1484)
	at org.zkoss.zk.ui.impl.UiEngineImpl.execUpdate(UiEngineImpl.java:1201)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.process(DHtmlUpdateServlet.java:558)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.doGet(DHtmlUpdateServlet.java:456)
	at org.zkoss.zk.au.http.DHtmlUpdateServlet.doPost(DHtmlUpdateServlet.java:464)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
	at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
	at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:401)
	at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
	at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
	at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:766)
	at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:450)
	at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
	at org.mortbay.jetty.Server.handle(Server.java:326)
	at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
	at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:945)
	at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:756)
	at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
	at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
	at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:410)
	at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Caused by: java.lang.NullPointerException
	at org.zkoss.zk.ui.AbstractComponent.addMoved(AbstractComponent.java:478)
	at org.zkoss.zul.Listitem.addMoved(Listitem.java:332)
	at org.zkoss.zk.ui.AbstractComponent.setParent(AbstractComponent.java:1055)
	at org.zkoss.zk.ui.AbstractComponent.insertBefore(AbstractComponent.java:1152)
	at org.zkoss.zul.Listbox.insertBefore(Listbox.java:1591)
	at org.zkoss.zul.impl.ListboxDataLoader.doListDataChange(ListboxDataLoader.java:107)
	at org.zkoss.zkmax.zul.impl.LiveListboxDataLoader.doListDataChange(LiveListboxDataLoader.java:95)
	at org.zkoss.zul.Listbox.onListDataChange(Listbox.java:2541)
	at org.zkoss.zul.Listbox.access$17(Listbox.java:2523)
	at org.zkoss.zul.Listbox$4.onChange(Listbox.java:459)
	at org.zkoss.zul.AbstractListModel.fireEvent(AbstractListModel.java:60)
	at org.zkoss.zul.ListModelList.add(ListModelList.java:162)
	at org.zkoss.zktest.bind.issue.B00871BeanInSession2.doButton(B00871BeanInSession2.java:40)