I just went through this, again... X11 touchscreen calibration seems to be a lost art. For whatever reason, the available X11 applets seems to be messed up somehow and has not been fixed. I had reasonable success with the adafruit app:
https://learn.adafruit.com/adafruit-2-4-pitft-hat-with-resistive-touchscreen-mini-kit/touchscreen-install-and-calibrate#x-calibration-2859025-23
Basically you need to download xtcal and install the pre-reqs and built xtcal. I do not know how easy that will be with the 0.4b or even the 0.5b image, today.
If the image has the xinput_calibration package installed (I have no idea if it is on any of them), you can use a very nice perl script to calibrate it.
http://support.fccps.cz/download/adv/frr/matrix_calibrator/matrix_calibrator.htm. The pre-req ia perl (installed) and xinput and xinput_calibrator, I believe. This works quite well (Version 1.2) and gives a very accurate calibration for the tiny screen I am using.
To run it, ssh into the rune and verify if the pre-reqs are installed:
pacman -Q | grep xinput
if it responds with something like this:
xinput_calibrator 0.7.5.r88.g03dadf5-1
xorg-xinput 1.6.3-2
you are equipped with the pre-reqs
then download the script and run it:
wget http://support.fccps.cz/download/adv/frr/matrix_calibrator/matrix-1.2.tgz
tar -xvf matrix-1.2.tgz
DISPLAY=:0.0 ./matrix.pl
and follow the instructions to create a calibration for the screen.
