ZK Developers can mix ZK components with standard HTML tags, and they are send direct to client display.Thus you can not control the native components on server side. (If you want to do so, please consider using XHTML Component Set.)
More details in ZK Developer's Reference - The native Namespace

<zk xmlns:n="native">
	<vlayout>
		<n:table border="1" cellspacing="2" cellpadding="10">
			<n:th>
				<n:td>HTML</n:td>
				<n:td>Code</n:td>
				<n:td>Result</n:td>
			</n:th>
			<n:tr>
				<n:td>Bold Text</n:td>
				<n:td>&amp;lt;b></n:td>
				<n:td>&amp;lt;n:b></n:td>
				<n:td>
					<n:b>This is Text</n:b>
				</n:td>
			</n:tr>
			<n:tr></n:tr>
		</n:table>
	</vlayout>

	With ZK Components
	<n:table border="1" cellpadding="10">
		<n:tr>
			<n:td>UserName</n:td>
			<n:td>
				<textbox id="name" value="zker"/>
			</n:td>
			<n:td rowspan="2">
				<button label="Info" onClick='alert(name.getValue() + " - " + mail.getValue())' />
			</n:td>
		</n:tr>
		<n:tr>
			<n:td>Email</n:td>
			<n:td>
				<textbox id="mail" value="info@zkoss.org"/>
			</n:td>
		</n:tr>
		<n:tr></n:tr>
	</n:table>
</zk>