On my Macbook I can only move the cursor while also pressing the touchpad after a default install. A per login session fix is to run "synclient FingerLow=10" and "synclient FingerHigh=20".
In order to make this change permanent I'm supposed to do add the following in the tochpad section of /usr/lib/X11/xorg.conf.d/10-synaptics.conf. But I do not have this file.
Section "InputClass"
Identifier "touchpad catchall"
MatchIsTouchpad "on"
MatchDevicePath "/dev/input/event*"
Driver "synaptics"
Option "FingerLow" "10"
Option "FingerHigh" "20"
EndSection