The folder rollover above is simple to implament, simply place 2 images into your images directory and name them as follows
The up and the down image have the same name except that the down image has an underscore before the file extension.
Example: folder.gif, folder_.gif
The following must be placed in the head of the html document.
<script src="preload.js"></script>
<script src="chgimg.js"></script>
