<zk>
	<window apply="org.zkoss.bind.BindComposer"
		viewModel="@id('vm')@init('MyVM')"">
		<div form="@id('fx')
			@load(vm.selProduct)@save(vm.selProduct, before='save')">
			
			<button label="click" onClick="@command('save')"/>
		</div>
	</window>
</zk>

		public class MyVM {
			private String selProduct;
			public String getSelProduct() {
				return selProduct;
			}

			public void setSelProduct(String selProduct) {
				this.selProduct = selProduct;
			}
		}