At least it did not fall onto your head..
No, just my nuts. Don't worry, it landed softly.
So here's the deal. The stylus seems to use absolute coordinates so it doesn't need to be calibrated? I may be wrong on this one.
It's the finger touch aspect that needed tweaking in my case. The problem is, this took several tries to get the right values
and I don't know why.
Run xinput_calibrator --list to figure out what is the device name for the touch device.
root@cf-19:/home/commander# xinput_calibrator --list
Device "Wacom ISDv4 93 Pen stylus" id=9
Device "Wacom ISDv4 93 Finger touch" id=10
Device "Wacom ISDv4 93 Pen eraser" id=15
Just note the id number, 10 with the above example. You probably need a regular touch screen stylus or another pointy object to calibrate the Finger touch device. This won't work properly with the digitizer pen. Run xinput_calibrator while specifying the device ID number and tap on the crosses as usual. Sudo or su as needed of course.
sudo xinput_calibrator --device 10
You now have calibration values. Note only the min and max X and Y values.
Option "MinX" "207"
Option "MaxX" "4008"
Option "MinY" "17"
Option "MaxY" "3800"
Option "SwapXY" .etc..... irrelevant stuff
Notice that after running this, it does absolutely nothing. Your touch screen is still not calibrated. You have to transcribe the min-max values as arguments to the xsetwacom program. The thing is, xsetwacom accepts the min-max values in different order. First both Min values, then the Max numbers. Of course, use your own calibration numbers. What follows bellow matches what I got above and may not apply to you but I surmise that it should be similar. If you get negative values or numbers very dissimilar to what I got, it probably won't work. I really had to try several times!
xsetwacom --set 10 Area 207 17 4008 3800
Now you should be calibrated if xinput_calibrator didn't screw up and gave you wrong numbers. Otherwise try again before making the changes permanent.
And to make it permanent, put the above command in a text file and dump it in /etc/X11/Xsession.d . I created a file 10-wacom (use your favourite text editor) as sudo or root and saved it in the Xsession.d directory. It should only contain the xsetwacom command with your Area values like the one above. As usual, preface the command with sudo or run as root with nano, pico or whatever text editor you use. Personally I use vi out of habit.
sudo nano /etc/X11/Xsession.d/10-wacom