<zk>
	<borderlayout vflex="min">		
		<center>
			<div height="200px">
				Click <button label="invalidate south" onClick="southRegion.invalidate()" /> button, should not see any JS error.
			</div>
		</center>
		<south id="southRegion" vflex="min">
			<div>South</div>
		</south>
	</borderlayout>
</zk>