AjaxControlToolkit.ModalPopupExtender.ChangeVisibility C# (CSharp) Метод

        private void ChangeVisibility(bool show)
        {
            if(TargetControl == null)
                throw new ArgumentNullException("TargetControl", "TargetControl property cannot be null");

            var operation = show ? "show" : "hide";

            if(ScriptManager.GetCurrent(Page).IsInAsyncPostBack)
                // RegisterDataItem is more elegant, but we can only call it during an async postback
                ScriptManager.GetCurrent(Page).RegisterDataItem(TargetControl, operation);
            else {
                // Add a load handler to show the popup and then remove itself
                var script = string.Format(CultureInfo.InvariantCulture,
                    "(function() {{" +
                        "var fn = function() {{" +
                            "Sys.Extended.UI.ModalPopupBehavior.invokeViaServer('{0}', {1}); " +
                            "Sys.Application.remove_load(fn);" +
                        "}};" +
                        "Sys.Application.add_load(fn);" +
                    "}})();",
                    BehaviorID,
                    show ? "true" : "false");
                ScriptManager.RegisterStartupScript(this, typeof(ModalPopupExtender), operation + BehaviorID, script, true);
            }
        }