Comment 13 for bug 1715479

run xinput list to find the device name, I wonder if I mistyped anything. then substitute the device name with the one for the touchpad. if you see devices like "wayland pointer" etc, then you're under wayland, in which case the xinput approach won't work. log out and back in as Gnome on Xorg on the user's login screen (click the gear icon), then see if you can reproduce it there.