Widget generates thumbnails even for non-image files

swfupload_widget.inc

  // Make sure that the thumbnails exist. $element['#value'] is
  // structured differently in our widget, so this is not handled by
  // imagefield_widget_process().
  if (is_array($element['#value'])) {
    foreach (element_children($element['#value']) as $key) {
      if (isset($element['#value'][$key]['filepath'])) {
        $file = $element['#value'][$key];
        swfupload_thumb_path($file, TRUE);
      }
    }
  }

There is no validation for image files.

It should be

      if (isset($element['#value'][$key]['filepath']) && image_get_info($element['#value'][$key]['filepath'])) {
        $file = $element['#value'][$key];
        swfupload_thumb_path($file, TRUE);
      }

On my site I have file_field for archives (max upload 100M). And swfupload_widget generates thumbnail for each of files uploaded.
1 file uploaded (100M) + thumb created (100M) = 200M