Cascading menu question

[Mark Swindell]

I have a menu which is called Appearance... one of the menuitems is "Set
background image to..." and I would like to have a cascading menu coming off
this which will display the contents of an image folder.  Choosing one of
these image files will then set the image of a graphic to that particular
file.

Can anyone explain to me how to accomplish this?

Thanks,
Mark