Hi, I’m using Leap 42.2 with Gnome 3.20.2. I cannot configure all features of the touchpad because the GUI is incomplete. It doesn’t look like written in the documentation . There are no sections for mouse and touchpad, only for the primary button. Do have any suggestions for full customizing of mouse and touchpad? As an alternative I have installed Gsynaptics  yet but I would like to fix the GNOME GUI.
I found out that GNOME 3.20 switched from synaptics to libinput. However there is synaptics-config file that must be deleted (I have renamed it). After that make a restart. Now you can config mouse and touchpad with the GNOME GUI. It seems to be a bug because the config file came with a clean new installation of Leap 42.2.
Another possibility is that the system was upgraded from 42.1, where xf86-input-synaptics was installed by default, the upgrade process not being designed to remove it.
So you have to remove xf86-input-synaptics manually when upgrading from 42.1 unless you already did so when libinput became available for 42.1.
Edit: I see now that the OP claims “the config file came with a clean new installation of Leap 42.2.” so I have to back Tyler_K’s assertion apparently…