/// <summary>
/// Downloads (pushes) file to the client browser. 
/// **** NOTE **** Cannot be done from inside an AJAX UpdatePanel control.
/// </summary>
/// <param name="fullFilePath">The full file path of the file</param>
protected void DownloadFile(string fullFilePath)
{
  // Gets the File Name
  string fileName = fullFilePath.Substring(fullFilePath.LastIndexOf('\\') + 1);
  byte[] buffer;
  using (FileStream fileStream = new FileStream(fullFilePath, FileMode.Open))
  {
    int fileSize = (int)fileStream.Length;
    buffer = new byte[fileSize];
    // Read file into buffer
    fileStream.Read(buffer, 0, (int)fileSize);
  }
  Response.Clear();
  Response.Buffer = true;
  Response.BufferOutput = true;
  Response.ContentType = "application/x-download";
  Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
  Response.CacheControl = "public";
  // writes buffer to OutputStream
  Response.OutputStream.Write(buffer, 0, buffer.Length);
  Response.End();
}