ASP.NET UpdatePanel CustomControl and PopupControlExtender odd issue - asp.net

Question

I am trying to use UpdatePanels, PopupControlExtenders, and a custom control to create a dropdown list of checkboxes. It works for the most part except for 1 odd glitch I cant seem to find a way around.
EnhancedCheckboxList.cs
Default.aspx
Default.aspx.cs
In order to replicate the glitch you have to perform the following actions in the order below.
Set A Dropdown to Role2
Set B Dropdown to Role2
Invert all A Authorities (Uncheck checked items and check unchecked items)
Set B Dropdown to Role1
View A Authorities (The items we unchecked in step 3 have become checked again)
For whatever reason unchecking the Authorities in step 3 has no effect but checking them does? I looked into getting the correct values from Request.Params but it doesnt look like that is giving me what I want. The glitch will only happen if you perform the steps in that order if you switch steps 2 and 3 it works fine.

Answer 1

Would you consider eliminating the UpdatePanels? I was able to reproduce the glitch using your original code. Once I removed the UpdatePanels the glitch is no longer reproducible:
<fieldset>
<legend>Role</legend>
<table width="500">
<tr>
<td>A</td>
<td valign="top">
<asp:DropDownList ID="Roles" runat="server" AutoPostBack="True" OnSelectedIndexChanged="roles_SelectedIndexChanged">
</asp:DropDownList>
</td>
<td valign="top">
<%-- <asp:UpdatePanel ID="UpdatePanel" runat="server">
<ContentTemplate>--%>
<asp:TextBox ID="txtAuthority" Text="Authorities" runat="server" CssClass="txtboxaschkbox" Visible="false"></asp:TextBox>
<asp:Panel runat="server" ID="PnlAuth" Visible="false" CssClass="PnlDesign">
<cc1:EnhancedCheckboxList ID="Authorities" runat="server">
</cc1:EnhancedCheckboxList>
</asp:Panel>
<cc2:PopupControlExtender runat="server" ID="PceSelectAuthority" TargetControlID="txtAuthority"
PopupControlID="PnlAuth" Position="Bottom"/>
<%-- </ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="Roles" />
</Triggers>
</asp:UpdatePanel>--%>
</td>
</tr>
<tr>
<td>B</td>
<td valign="top">
<asp:DropDownList ID="Roles2" runat="server" AutoPostBack="True" OnSelectedIndexChanged="roles2_SelectedIndexChanged">
</asp:DropDownList>
</td>
<td valign="top">
<%-- <asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>--%>
<asp:TextBox ID="txtAuthority2" Text="Authorities" runat="server" CssClass="txtboxaschkbox" Visible="false"></asp:TextBox>
<asp:Panel runat="server" ID="PnlAuth2" Visible="false" CssClass="PnlDesign">
<cc1:EnhancedCheckboxList ID="Authorities2" runat="server">
</cc1:EnhancedCheckboxList>
</asp:Panel>
<cc2:PopupControlExtender runat="server" ID="PceSelectAuthority2" TargetControlID="txtAuthority2"
PopupControlID="PnlAuth2" Position="Bottom"/>
<%-- </ContentTemplate>
<Triggers>
<asp:AsyncPostBackTrigger ControlID="Roles2" />
</Triggers>
</asp:UpdatePanel>--%>
</td>
</tr>
</table>
</fieldset>