The C1DialogExtender control formats a dialog box for displaying information. The dialog window can be moved, resized, and closed.
C1DialogExtender Markup
The following markup creates a C1DialogExtender control. Set the TargetControlID property to attach the extender to a control.
<cc1:C1DialogExtender ID="Panel1_C1DialogExtender" runat="server"
TargetControlID="Panel1">
</cc1:C1DialogExtender>