use a transparent background to let the users eye focus on the folder content (e.g. like in <a href="http://www.kde-look.org/content/preview.php?preview=1&id=60475&file1=60475-1.jpg&file2=&file3=&name=Crystal+Project">http://www.kde-look.org/content/preview.php?preview=1&id=60475
&file1=60475-1.jpg&file2=&file3=&name=Crystal+Project</a>)