This is a very unusual unit. It has a point-stick and touchpad. The pointstick has 3 keys and the touchpad has 2. The point-stick always seems to work; however the touchpad only seems to work intermittantly. The cursor will sometimes be frozen and sometimes it will jitter, never staying in the same place; other times, it will work for the entire session. It also misbehaves in the same way in Windows 10. Ordinarily, this would suggest a hardware problem to me; but the following Reddit post, seems to suggest otherwise.
This is a used unit, and other DELL Laptops of that vintage, 2011, have similar issues; so I'm reluctant to condemn the hardware just yet, especially since this unit was loaded for a power user and appears well cared for.
I have fedora core 25 on gnome.