Lubuntu 16.04 touchpad problems
I suggest installing libinput. It works better in 16.04, than the old xorg-synaptics.
Install it by
sudo apt install xserver-xorg-input-libinput
Tapping is disabled by default. If you need this feature, you can enable it by adding
Option "Tapping" "True"
to the touchpad section of /usr/share/X11/xorg.conf.d/90-libinput.conf