How to Show loading panel for radgrid with Custom Export to Excel option

Hi Team,

We are using Custom Export to excel button to export the Radgrid data to excel. While exporting the data we are trying to show the spinner during the export  but we are unable to catch the file downloaded event, So even the file downloads the spinner still continues to spin. Is there any other option to show waiting panel in this case. please help me on this. Please find the code below.

We tried with Auto Export excel option "<CommandItemSettings ShowExportToExcelButton="true" />" of radgrid. But it's showing the data on the screen in datatable format. we need the file to be downloaded. Not getting the file download option in this case.

.aspx

<td>
<asp:ImageButton ID="ExportToExcel" src="images/Excel.png" OnClientClick="showspinner();" runat="server" OnClick="ExportToExcel_Click" width="50"/>
</td>

.aspx.cs

RadGridMigrationReport.MasterTableView.ExportToExcel();