<div id="dlg">

        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

    </div>

       <asp:Button ID="Showdlg" runat="server" Text="..." />

    </form>

    <script type="text/javascript" language="javascript">

      $(function () {

             $("#dlg").dialog({

                autoOpen: false,

                closed: true,

                width: 450,

                modal: true,

                appendTo: "form",

                buttons: {

                    "OK": function () {

                        $("form").submit();

                    },

                    "Cancle": function () {

                        $(this).dialog("close");

                    }

                },

                close: function () {

                }

            });

            $("#<%=Showdlg.ClientID%>").button().click(function() { $("#dlg").dialog("open"); return false });

         }

        );

    </script>

</body>