CKEditor wih AjaxControlToolkit's ModalPopup - asp.net

Question

I have got *.ascx control with Ckeditor embedded by using CKEditor's control for ASP.NET (v 3.6.4). I have also ModalPopup control from AjaxControolToolkit4.5, attached to Link Button. When clicked, it shows panels with Radio Button list filled in with the aid of some code behind logic.
How should I change my *.ascx control to have a CKEditor'a plugin button in toolbar, firing this ModalPopup?
Code (not working):
<%# Control Language="C#" AutoEventWireup="true" CodeFile="CKEditorWithModalPopup.ascx.cs" Inherits="Controls_CKEditorWithModalPopup" %>
<%# Register Assembly="CKEditor.NET" Namespace="CKEditor.NET" TagPrefix="CKEditor" %>
<%# Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="ajaxToolkit" %>
<script type="text/javascript">
$(function () {
var a = {
exec: function (editor) {
javascript: __doPostBack('ctl03$LinkButton1', '') // explicite id for test
}
},
b = 'modalPopup';
CKEDITOR.plugins.add(b, {
init: function (editor) {
editor.addCommand(b, a);
editor.ui.addButton("modalPopup", {
label: 'Modal Popup',
icon: "~/Images/modal_popup.png",
command: b
});
}
});
});
</script>
<CKEditor:CKEditorControl ID="CKEditor1" BasePath="~/ckeditor" Toolbar="Basic" runat="server" />
<ajaxToolkit:ModalPopupExtender ID="ModalPopupExtender" runat="server" TargetControlID="LinkButton1"
PopupControlID="Panel1" BackgroundCssClass="modalBackground" OkControlID="OkButton"
CancelControlID="CancelButton" DropShadow="true" PopupDragHandleControlID="Panel3" />
<asp:LinkButton ID="LinkButton1" runat="server" Text="Click here to change the paragraph style" />
<asp:Panel ID="Panel1" runat="server" Style="display: none" CssClass="modalPopup">
<asp:Panel ID="Panel3" runat="server" Style="cursor: move; background-color: #DDDDDD;
border: solid 1px Gray; color: Black">
<div>
<p>
Choose the phrase to insert:</p>
</div>
</asp:Panel>
<asp:RadioButtonList ID="rbList" runat="server" />
<p style="text-align: center;">
<asp:Button ID="OkButton" runat="server" Text="OK" />
<asp:Button ID="CancelButton" runat="server" Text="Cancel" />
</p>
</asp:Panel>

Answer 1

I found better solution for CKEditor modal popup functionality - I decided to write it as CKEditor plugin. It is much easier and maintainable approach.
Creating a CKEditor Plugin with a Custom Dialog Window
The purpose of this answer is to close the old question.