The tablet is the Intuos 3 (YSB).
The libwacom libraries are installed.
On Gimp the drawing is as expected, The pen & tablet are recognised by Gimp, I can set a curve, I did not found out yet how to see effects of these settings.
The OS is Raspbian Jessie with all updates. (It is not the most recent image 2017-02-16 because with that image the wacom is not responding at all) Linux 4.9.11-v7+