protected override void OnPreRender(EventArgs e)
{
// Get the associated BaseValidator and set ClientState accordingly
var baseValidator = TargetControl as BaseValidator;
if((baseValidator != null) && !baseValidator.IsValid)
ClientState = "INVALID";
else
ClientState = String.Empty;
base.OnPreRender(e);
ResolveControlIDs(_onShow);
ResolveControlIDs(_onHide);
}