There is a little bug in line 170 of controlpanel.module :


 $content .= '<img src="' . base_path() . $src . '" alt="'. $menu_item['link']['title'] .'" title="'. strip_tags($menu_item['link']['description']) .'" />';

must be :


 $content .= '<img src="' . base_path() . $src . '" alt="'. $menu_item['link']['title'] .'" title="'. check_plain(strip_tags($menu_item['link']['description'])) .'" />';

else if you have special chars in description, they can make problems (like description in 'Page' content type, it contains " and break the title attribute of img tag, check it with w3 validator)