Touchpad palm sensitivity

AFAIK, palm sensing is not exposed through the graphical touchpad configuration tool. That said, you could try playing with it by using synclient.

To see what options are available, run synclient -l | grep -i palm

PalmDetect              = 0
PalmMinWidth            = 10
PalmMinZ                = 200

Those are the options I see, so, to activate the palm sensing, run synclient PalmDetect=1, and then experiment with the values of the other two.

   "PalmMinWidth" "integer"
          Minimum finger width at which touch is considered a palm.  Prop‐
          erty: "Synaptics Palm Dimensions"

   "PalmMinZ" "integer"
          Minimum  finger  pressure  at  which touch is considered a palm.
          Property: "Synaptics Palm Dimensions"

When you find the right values, create a startup entry in Startup Applications with a command of the following form:

synclient PalmDetect=1 PalmMinWidth=xx PalmMinZ=yy

...where xx and yy are the desired values.