How to get cursor on a textbox under an update panel

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C#

ASP.NET

UpdatePanel

I have two textbox under an update panel that is refresh periodically. When it refresh I lost cursor from the textbox I was typing. How to get the cursor on the textbox i was typing after refresh it.

<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
 <asp:UpdatePanel ID="UpdatePanel1" runat="server">
     <ContentTemplate>

         <asp:Timer ID="updateTimer" runat="server" Interval="5000" OnTick="updater_Tick">
         </asp:Timer>
         <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

         <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>

     </ContentTemplate>
 </asp:UpdatePanel>