"So far, nobody has filled in the section on how a key-press event works its way through the OS, up to the window system, to the application, and to the code ha

"So far, nobody has filled in the section on how a key-press event works its way through the OS, up to the window system, to the application, and to the code handling the input text box." That in itself is a multi-year discussion. From silicon chemistry theory, voltage biasing different types of substrates, the definition of ground, all the way to sofware control loops, eventing, software emulating parallellism, all the things happening and just waiting to happen on a single OS before you even press "g" on the keyboard will blow most people's minds away.