<zk>
<html><![CDATA[
<ol>
<li>Type "aa" in the datebox, then press "tab" key</li>
<li>You can see "error1" in the below of datebox.</li>
<li>Delete "aa" in the datebox, then press "tab" key</li>
<li>You can see "error2" in the below of datebox.</li>
</ol>
]]></html>
<zscript>int i = 1;</zscript>
<datebox format="dd-MMM-yyyy"
onError='msg.value = "error" + (i++);'/>
<separator height="50px"/>
<label id="msg"/>
</zk>
http://tracker.zkoss.org/browse/ZK-197