title: How to display a progress status/spinner when outputting file via Response.ContentType, Response.End?
body: <p>I have a webform with a <strong>Download LinkButton</strong>, on the button's click event I'm fetching data and then <strong>generating an .XLSX file</strong> for download. During the generation of the file, <strong>Response.Clear()</strong> is called, <strong>Response.ContentType</strong> is set and eventually <strong>Response.End()</strong> is called.</p>
  
  <p>I need to <strong>display a spinner .gif</strong> during that operation. Once the file has been generated and the file "Open/Save" dialog pops up, the <strong>spinner should not display</strong>. Unfortunately, since I'm changing the content type and calling Response.End there is no response returned back to the page to work with.</p>
  
  <p><strong>Can anyone please provide a little help with this scenario?</strong></p>