Ello.
What I have is an UpdatePanel containing two Panels which each contain differing server controls. And based upon a drop down list the user will determine what panel will be displayed.
<asp:ScriptManager ID="MyScriptManager" runat="server" EnablePartialRendering="true"></asp:ScriptManager>
<asp:UpdatePanel ID="executionItemsPanel" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<!-- First Panel -->
<asp:Panel ID="Panel1" runat="server">
<asp:Label ID="lbl_uno" runat="server">First Label</asp:Label> <br />
<asp:DropDownList ID="uno" runat="server"></asp:DropDownList>
<asp:Label ID="lbl_dos" runat="server">Second Label</asp:Label> <br />
<asp:dropdownlist ID="HeyLookAdropDown" runat="server" Enabled="false">
<asp:ListItem Text= ...
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