<zk>
	<window title="Window1" border="normal" id="win" width="600px">
		<hlayout hflex="1" id="h">
			<vlayout hflex="1">
				<label value="Listbox A"/>
				<listbox hflex="1">
					<listitem label="A1"/>
					<listitem label="A2"/>
				</listbox>
			</vlayout>
			<vlayout hflex="1" id="d" visible="false">
				<label value="Listbox B"/>
				<listbox hflex="1">
					<listitem label="B1"/>
					<listitem label="B2"/>
				</listbox>
			</vlayout>
		</hlayout>
		<button label="toggle" onClick="d.visible = !d.visible;" />
	</window>
</zk>