Gnome Touchpad Settings Missing in Arch (XPS 13 9360)
I had an issue where the Gnome extension 'Touchpad Indicator' stopped working on my XPS 13 (Arch). After looking a bit further, it seems that the Gnome Touchpad settings had also stopped working. All I could see was the mouse settings, and the touchpad section was completely gone.
With Gnome 3.20, xf86-input-synaptics is not longer supported, and you should use xf86-input-libinput instead.
You can check what is installed on your Arch system with pacman -Q | grep input. In my case, I had both packages installed: