in order to make this work you have to have the images as shown in the code. Either you could define your own images or if you really want to see it working the way it is mail me at firstname.lastname@example.org and i will mail you the images.
The next js file is called menutree.js which is used to initialize the array and customise the folder tree view. Here is a small example of what i have done:
With all that in place you are ready to test out the Folder Tree View just like the one in Windows Explorer. Go ahead and enjoy. If you have any questions or concers feel free to mail me at email@example.com.