ASUS ROG G750 and Fn-Keys and Touchpad

Support
1

Manjaro Linux 64-Bit, XFCE-Version 4.16

Hello,
on my Asus ROG G750JS i can’t disable my touchpad by using Fn+F9.
I can only disable the touch function in the mouse-/touchpad settings.

is there a fix for this know?

greetings from germany
Heiko