WordPress Download Monitor generates mixed content on https-sites in wp-admin due to $wp_dlm_root (bar.png and media-button-download.gif).
If personally fixed this by adding
if (is_ssl()){
$wp_dlm_root = str_replace( 'http://', 'https://', $wp_dlm_root );
}
to wp-download_monitor.php, but it would be nice if you could include this in the next update.
Greetings.