"
<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:TextBox ID="txtName" runat="server"></asp:TextBox>
<asp:Panel ID="Panel1" runat="server">Hello</asp:Panel>
<asp:BalloonPopupExtender ID="BalloonPopupExtender1" runat="server" BalloonPopupControlID="Panel1" TargetControlID="TxtName" BalloonStyle="Cloud">
</asp:BalloonPopupExtender>
"