Is "Fn key" not defined in X Window in "X11/keysymdef.h"?

Question

I tried to simulate keypress by Xlib, but I can't find out where Fn key was defined in " keysymdef.h ".

If it really wasn't defined in Xlib, are there any workarounds for it ?

Answer 1

Fn works differently from modifiers such as Shift: it's typically caught inside the keyboard controller or in the BIOS, and the combined (Fn + other) keypress is sent over the bus as a single signal. That means that X11, or the OS for that matter, doesn't even get to see that Fn was pressed.