PhotoBox is simply an example of what you could build as a custom implementation of Panel, to demonstrate the fact that you can extend its behavior and user interface. It’s not included in the documentation because it’s not packaged as a control in the library, primarily because it’s not a fully developed control, but rather a simple example. If you have any questions about how it works, feel free to ping me and I’ll be glad to try and help you. Otherwise, you should be able to look at the source code for PhotoBox at: http://developer.yahoo.com/yui/examples/container/js/PhotoBox.js for a rough idea of how it works.
Web Developer, Platform Engineering