Custom Interface

Well basically I had this idea to make a new custom interface, or at least a "skin" ... anyway I guess you guys know what I`m talking about =p But before I start working on this I`ll need to know a few things ... such as: In what .pck files are the files of the interface located? Are they all in the interface.pck or are there also parts in surfaces.pck? So what I basically would like to know is ... Where are all the files that have something to do with the interface located?

Guide

both surfaces and interfaces