So, I didn't play with touchpad too much after installing Kali 2.0 on my Acer C720 Chromebook (see previous post). It turns out that the touchpad sensitivity to fingers is pretty high by default, which means that it doesn't always register finger movements and taps. There is a fix to this in the synaptics settings, and there a few ways to get to it.
First, the command synclient will show all of the related settings. Type it into a command line and see. The settings that control sensitivity are "FingerHigh" and "FingerLow". By default, FingerLow is set to 25 and FingerHigh is set to 30. So, use the command:
root@pc:~# synclient | grep -e 'Finger'
This will a handful of settings, including FingerHigh and FingerLow. To temporarily change them, use the command synclient <variable>=<value>.
root@pc:~# synclient FingerLow=6
root@pc:~# synclient FingerHigh=10
If you try to set FingerHigh=10 before moving FingerLow to 6, then the system will complain. That is because you are trying to set the "high" value (30->10) lower than the "low" value (25). So change low to 6, then high to 10.
Try other values and see if they work better. Once you have found good values, make them permanent by adding them to the /usr/share/X11/xorg.conf.d/50-synaptics.conf file.
Add the following section, or just the missing lines if it is already there:
Section "InputClass"
Identifier "touchpad catchall"
Driver "synaptics"
MatchIsTouchpad "on"
MatchDevicePath "/dev/input/event*"
Option "FingerLow" "10"
Option "FingerHigh" "16"
EndSection
My file already had the first three lines, so I just had to insert:
MatchDevicePath "/dev/input/event*"
Option "FingerLow" "10"
Option "FingerHigh" "16"
After that, restart X11. I just rebooted the system. Don't forget to put the "*" at the end of the MatchDevicePath line!
