I think that SDL or QT might have the most compatible list
SDL does in C what Squeak 6.0alpha already does in Smalltalk. Looking at "SDL_x11keyboard.c" or "scancodes_windows.h", we have in `EventSensor >> virtualKeyTable`.
Now, SDL has its own `KeySymToSDLScancode` table. In this PR, I chose to simplify matters by just converting the special keys from 0xff__ to 0x00__ plus using the room between 0x20 and 0x4f for alpha-numeric keys. So that we stay in 1 byte, just as macOS and Windows do.
Also, SDL uses a similar "hack" for alpha-numeric keys. See SDL_x11keyboard.c function "X11_KeyCodeToSDLScancode".
This PR is als complete as in can get for X11. I am currently fixing up some modifier issues when pressing only modifier keys.