> X Windows does _not_ use network for drawing, but only to exchange window details like position, size and atoms.
Actually, it does.
With lots of ways to do it, from simple zero-width lines to antialiased trapezeoids in X-render. With lots of complicated code which runs in the X-server, with the root privileges. Here's documentation for some of it: http://tronche.com/gui/x/xlib/graphics/
In short, it's been known for ages that the X server is about as holey as Swiss cheese.