<window>
	<button id="btn" label="button"/>
	<button label="show/hide" onClick="btn.setVisible(!btn.isVisible());"/>
	<script defer="true">
	var btn = zk.Widget.$("$btn");
	zWatch.listen( {
	onHide: [
	btn, function(){zk.log("[zWatch]onHide "+this.id)}
	]
	,onShow: [
	btn, function(){zk.log("[zWatch]onShow "+this.id)}
	]
	});
	btn.listen({
	onHide: function(){zk.log("[Widget]onHide "+this.id)}
	,onShow: function(){zk.log("[Widget]onShow "+this.id)}
	});
	</script>
</window>