Using an ajax:ModalPopup Without a TargetControl

The ModalPopup extender usually requires a control for firing up, set through the TargetControlID property. However, sometimes you may want to show and hide the panel programmatically. All you need is a fake activator, like the following:

The Extender

<ajax:ModalPopupExtender ID="mpeInfo" runat="server" TargetControlID="divFakeActivator"
    PopupControlID="pnlInfo" CancelControlID="bttInfoClose" />

The Panel

<asp:Panel ID="pnlInfo" runat="server">
    Hello World!!!
</asp:Panel>

The C# code

// Show and hide programmatically
mpeInfo.Show();
mpeInfo.Hide();

Note (2025): This post reflects an older ASP.NET AJAX pattern. In modern frameworks you would likely manage modal dialogs through client‑side libraries (e.g., Bootstrap, React, Blazor components).