function onSourceDownloadProgressChanged(sender, eventArgs)
{
  var rectBar = sender.findName("RectBar");
  var rectBorder = sender.findName("RectBorder");
  var percent = sender.findName("ProgressText");
  var progress;

  if (eventArgs.progress)
    progress=eventArgs.progress;
  else
    progress=eventArgs.get_progress();

  rectBar.Width = progress * rectBorder.Width;
  percent.Text = Math.round(progress * 100) + "%";
}