AjaxControlToolkit.ValidatorCalloutExtender.OnPreRender C# (CSharp) Метод

        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);
        }