if (attr == null)
throw new UiException("The name attribute required, "+el.getLocator());
final String attnm = attr.getValue();
noEmpty("name", attnm, el);
final ConditionImpl cond = ConditionImpl.getInstance(
el.getAttributeValue("if"), el.getAttributeValue("unless"));
if (bNativeContent) {
if (Events.isValid(attnm))
throw new UiException("Event listeners not support native content");