Actually, could you clarify what you mean by this part?

Quote:Various protocols are available under X to remap keys and alter response to key input (alt, ctrl, meta, et al.)

Are you assuming that key events are filtered at runtime by the program that remaps them? I always thought that tools like xbindkeys change "the key map" and then quit. Like changing the keyboard layout from qwertz to qwerty. But I never had a deeper look at the details here.