ZK comboboxes allow developers to add other ZK components in their drop down menu; shown as an example here, a listbox with paging feature.

This demo use bandbox component, which allows user create any content on it's popup.

<zk>
	<zscript><![CDATA[
		String[] languages = {"Ada","Basic","C","C++","CSS","Cobol","Forth","Fortran",
			"Go","Groovy","Haskell","HTML","Java","JavaScript","Lisp","Python","Ruby",
			"Scala","Scheme"};
	]]></zscript>
	<bandbox id="bd" mold="rounded" autodrop="true">	
		<bandpopup>
			<listbox height="250px" width="450px" mold="paging" autopaging="true"
				onSelect="bd.value=self.selectedItem.label; bd.close();">
				<listhead>
					<listheader label="Programming Languages" />
				</listhead>
				<listitem label="${each}" forEach="${languages}" />
			</listbox>
		</bandpopup>
	</bandbox>
</zk>

<vlayout>
	<checkbox checked="true" label="Enable Auto Drop-down"
		onCheck="bd.autodrop = self.checked" />
	<checkbox checked="true" label="Make Button Visible"
		onCheck="bd.buttonVisible = self.checked" />
</vlayout>