The GFX files are created with the Adobe Scaleform product. The SWF files can be modified using any standard Flash tool.
There are two major types of files used, SWF and GFX. You can use Fallout Mod Manager to extract the files from the BSA. The GUI files can be found in the 'Skyrim - Interfaces.bsa' file in your game's Data directory. The format is SWF 10 and the scripts are written in ActionScript 2.0. The Skyrim GUI uses Adobe Flash and Scaleform. You can put requests in here too, but please try to keep form turning this into a GUI bashing thread. This thread is for technical discussions surrounding modding the GUI.
