Randy’s computer runs Finux, so when it boots up it gives him a black screen with big fat white letters scrolling up it one line at a time, a real circa-1975 type of user interface. Also presumably the easiest possible thing to read through Van Eck phreaking. Randy types in "startx" and the screen goes black for a moment and then turns a particular shade of indigo that Randy happens to like, and beige windows appear on it with much smaller and crisper black letters. So now he is running the X Windows System, or X as people like Randy call it, which provides all of the graphical junk that people expect in a user interface: menus, buttons, scroll bars, and so on. As with anything else under UNIX (of which Finux is a variant), there are a million options that only young, lonely, or obsessed people have the time and patience to explore. Randy has been all three at various times of his life and knows a lot about these options. For example, the background of his screen happens to be a uniform indigo at the moment, but it could be an image. Theoretically you could use a movie, so that all of your windows and menus and so on would float around on top of, say, Citizen Kane running in an endless loop. You can, in fact, take any piece of software and make it into your screen background, and it will purr along happily, doing whatever it does, and not even known that it’s being used as window-dressing. This has given Randy some ideas on how to approach the Van Eck thing.