AjaxControlToolkit.TextBoxWatermarkExtender.OnLoad C# (CSharp) Method

        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);

            // Register an empty OnSubmit statement so the ASP.NET WebForm_OnSubmit method will be automatically
            // created and our behavior will be able to wrap it for watermark removal prior to submission
            ScriptManager.RegisterOnSubmitStatement(this, typeof(TextBoxWatermarkExtender), "TextBoxWatermarkExtenderOnSubmit", "null;");

            // If this textbox has default focus, use ClientState to let it know
            ClientState = (string.Compare(Page.Form.DefaultFocus, TargetControlID, StringComparison.OrdinalIgnoreCase) == 0) ? "Focused" : null;
        }