i wanted to change the icons in /usr/local/share/xfe/icons/windows-theme
but thumbnails are only shown for those 10 files that actually lie in that folder, the others are linked to ../xfe-theme and no thumbnail is shown (but the ugly chain icon instead)
i'd suggest using the original icon anyway, and just overlay a small arrow for links, like its done in the windows explorer.
this way also a link to a folder would look in a consistent way.
btw, great work !