asp.net How Do I Change a Cursor From Wait Back to Normal After a Server Process Has Executed With No Postback?

I have a website that, after the user clicks an Imagebutton, calls server side code to create an Excel file and downloads it. This process can take about 20 seconds to finish so I’m wanting to change the cursor to wait mode until it finishes. I’ve followed the guidelines in this post, but it fails to say how I can reset the cursor back to normal once the download is complete.

Below is the last part of my server side code that actually creates the download, is there something I can possibly do to check the HTTPContext to see if it’s finished?

//*****************************************
//* Workbook Download & Cleanup
//*****************************************
using (var stream = new MemoryStream())
{
    Response.Clear();
    wb.Write(stream);
    Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
    Response.AddHeader("Content-Disposition", string.Format("attachment;filename={0}", "Student Experiences.xlsx"));
    Response.BinaryWrite(stream.ToArray());
    Response.Flush();
    Response.End();
    HttpContext.Current.ApplicationInstance.CompleteRequest();
}