you need 3 programs to edit interface
1: with WOTgrealExporter you can DECOMPILE interface.u ( it will give you a folder with all the classes you are looking at right now with utpt
2: compiler for interface.u ( for interlude ) so you can SAVE the changes you make in the .uc ( scripts that tell each window what to do ) and make a new interface.u file with the changed classes.
3: xdateditor ( to edit interface.xdat file in the system folder ) to edit anything that has to do with visual client side thing. window sizes, positions, buttons, textures, shortcuts etc.
Link for WOTgrealExplorer : https://yadi.sk/d/m52OTEEls6v8H
Link for compiler : search this forum it was shared somewhere, if you cant find it let me know i'll try to find it.
Link for xdateditor : https://sites.google.com/site/l2clientmod/xdat_editor