I mostly learned programming GUI applications, in Xwindow and in general, studying the code of xv. The GUI controls were written from scratch using X resources and the code quality was top notch. I remember printing the full source code back in the winter break of 1994 at my university printers since I was going on vacations with my family and I was going to be completely disconnected. I studied the code writing side notes every time I had a moment to relax. Good times. Many thanks, John.