Open and close Radwindow

Write Script in design page:

<script type="text/javascript">

        function Open(win) {

            var window = document.getElementById(win);

            window.control.Show();

        }

        function Close(win) {

            var window = document.getElementById(win);

            window.control.Close();

        }

    </script>

Write the code in Code behind of your page:

private void OpenPopUp()

        {

            string script = "function f(){Open('" + radwindowAddCategory.ClientID + "'); Sys.Application.remove_load(f);}Sys.Application.add_load(f);";

            ScriptManager.RegisterStartupScript(Page, Page.GetType(), "key", script, true);

        }

        private void ClosePopUp()

        {

            string script = "function f(){Close('" + radwindowAddCategory.ClientID + "'); Sys.Application.remove_load(f);}Sys.Application.add_load(f);";

            ScriptManager.RegisterStartupScript(Page, Page.GetType(), "key", script, true);

        }