<zk>
	<hlayout apply="org.zkoss.bind.BindComposer" viewModel="@id('vm') @init('TestVM')">
		<combobox model="@init(vm.countries)" selectedItem="@bind(vm.country)">
			<template name="model">
				<comboitem value="${each}" label="${each}" />
			</template>
		</combobox>
		<label value="@load(vm.country)" />
	</hlayout>
</zk>

public class TestVM {
	private String country;

	public String[] getCountries() {
		return new String[] { "ES", "FR", "IT", "UK" };
	}

	public String getCountry() {
		return country;
	}

	public void setCountry(String country) {
		this.country = country;
	}
}