xorg-x11-drv-libinput touchpad middle-click?

[Ian Pilcher]

With xorg-x11-drv-synaptics on F25, I used a 3-finger click on my
touchpad to emulate a middle-click.  This doesn't seem to work with
xorg-x11-drv-libinput on F26.  (I am using Plasma, so still on X.)

Is there a configuration option I can set somewhere to make this work,
or do I have to use the "synaptics-legacy" driver?