But with my little numeric keyboard I managed to control the menu AI traffic of fsx from 0 to 10 "no problem"
You mean the "ATC menu" ? That's ANOTHER menu, which might be handled differently by the sim.
But I can not do it with the menu gsx.
That's NOT a "GSX menu"!!! It's the standard 3rd party addons menu, also known as "Simconnect menu", so it's NOT anything that GSX has any control over it, except to choose the names of the choices.
In your configuration menu, you can not change the keys ... Only that of Ctrl F12. This is really a shame.
Obviously because, as I've said, it's NOT a "GSX menu"!!! It's the Simconnect menu, shared between all the 3rd party applications, that don't have ANY way to decide how to handle keys, and how to reassign them.
That's why you cannot find a way to configure it in the GSX keys, for the following two reasons:
1) It would be wrong that GSX would try to change an assignment which is common for every 3rd party in-game menu.
AND
2) Even if we could do that, it's not even possible, since the sim doesn't give 3rd party applications a way to redefine such keys.
As I've said, your only option is that your keypad would issue exactly the same key codes AS IF they were the numbers on the regular keyboard (no the numeric pad). If your keypad allows you to do that, it will surely work.