"Fancy box pop-up" is a integration of the well-know fancy box script. If you set item link url to image files(gif,jpg,jpeg,bmp,png) , click it will overlay images on the current page. You can control item list roll/image width/image height and other settings for for tweaking both behavior and appearance.
This feature works very similar like "Light box pop-up" , but it loads more fast, and you can use mouse wheel to navigate images. We recommend you use it to replace the "Light box pop-up" feature in most cases.