public class MyVM {

	private Data data = new Data();
	
	public Data getData() {
		return data;
	}
	
	public void setData(Data data) {
		this.data = data;
	}
	
	public Validator getValidator() {
		return new AbstractValidator () {

			public void validate(ValidationContext ctx) {
				String val = (String)ctx.getProperty().getValue();
				if (val == null || val.trim().length() == 0) {
					addInvalidMessage(ctx, "please type text");
				}
				
				 Component comp = ctx.getBindContext().getComponent();
		         if (comp != null) {
		        	 
		        	 System.out.println(comp + ": " + ctx.isValid());
		        	 
		             ((HtmlBasedComponent)comp).setSclass(
		                     ctx.isValid() ?  "": "red");
		         }
					
			}
			
		};
	}
	
	@Command
	public void save() {
	}
	
	public static class Data {
		private String value1 = "val1";
		private String value2 = "val2";
		
		public String getValue1() {
			return value1;
		}

		public void setValue1(String value) {
			this.value1 = value;
		}
		
		public String getValue2() {
			return value2;
		}

		public void setValue2(String value) {
			this.value2 = value;
		}
		
	}
}

<zk>
	<style>
		.red,
		.red .label-textbox-input {
			border: 1px solid red;
		}
		
		.label-textbox-macro {
			border: none;
		}
	</style>
	
	
	<window apply="org.zkoss.bind.BindComposer"
		viewModel="@id('vm') @init('foo.MyVM')"
		validationMessages = "@id('vmsgs')">
		
		<div form="@id('fx')
			@load(vm.data)
			@save(vm.data, before='save')">
		
			<vlayout>
				<textbox id="val1Tb"
					value="@bind(fx.value1)@validator(vm.validator)" />

				<textbox id="val2Tb"
					value="@bind(fx.value2)@validator(vm.validator)"/>
				
				<label value="@load(vmsgs[val1Tb])" />
				<label value="@load(vmsgs[val2Tb])" />
				
				<button label="save" onClick="@command('save')"/>
			</vlayout>
		
		</div>
	</window>
	
</zk>