Expand/Collpase window on button click

<zk xmlns:w="http://www.zkoss.org/2005/zk/client" >
	<window>
		<hbox id="hbox1" width="500px" height="500px" style="border: 3px solid red;">
			...
			Stuff goes in here
			...
		</hbox>
		<space height="25px"/>
		<button label="Click Me">
			<attribute w:name="onClick">
				jq(this.$f('hbox1')).slideToggle(500);
			</attribute>
		</button>
	</window>
</zk>

<?page id="ZKLoginDialog" title=" Login "?>
<?link rel="shortcut icon" type="image/x-icon" href="/favicon.ico" ?>
<?link rel="icon" type="image/gif" href="/animated_favicon1.gif" ?>
<?taglib uri="http://www.zkoss.org/dsp/web/core" prefix="c"?>

<zk xmlns="http://www.zkoss.org/2005/zul" xmlns:h="http://www.w3.org/1999/xhtml"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:w="http://www.zkoss.org/2005/zk/client"
	xsi:schemaLocation="http://www.zkoss.org/2005/zul http://www.zkoss.org/2005/zul/zul.xsd">


	<window id="loginwin" border="none" width="475px" apply="org.opentruuls.base.webui.login.ZkLoginDialogCtrl">

		<script type="text/javascript">

			<![CDATA[ function submit() { document.f.submit(); } ]]>

               </script>

  // Rest of zul components here

	</window>
</zk>

	/**
	 * when the "login" button is clicked. <br>
	 * 
	 * @throws IOException
	 */
	public void onClick$btnLogin() throws IOException {

   . . .

	Clients.evalJavaScript("submit()"); // do submit
	}