Comment # 6 on bug 913016 from jean-christophe baptiste

Thank you for checking.

I finally found how to make it work :

1. Install the xf86-input-libinput, which is not installed by default.

2. Edit /etc/X11/xorg.conf.d/50-synaptics.conf to add 2 lines in the section
for clickpads to enable the wheel :

Option       "EmulateWheel"       "1"
Option       "EmulateWheelButton" "2"

The section should look like this:

Section "InputClass"
        Identifier "Default clickpad buttons"
        MatchDriver "synaptics"
        Option "SoftButtonAreas" "50% 0 82% 0 0 0 0 0"
        Option "SecondarySoftButtonAreas" "58% 0 0 15% 42% 58% 0 15%"
        Option       "EmulateWheel"       "1"
        Option       "EmulateWheelButton" "2"
EndSection

While it is nice that it works, I think that on this point the life should be
made easier for the average user.