I have a Monoprice drawing tablet and I'm using Ubuntu 18 with a Gnome-based GUI. Other than this issue it works fine.
WITHOUT CHANGING ANY OF THE ABOVE:
The default is tablet mode (the tablet corresponds directly to the screen) and I want to use it in mouse mode (the cursor doesn't move when I pick up and move the pen) but can't work out how to change that setting.
Settings > Devices > Wacom Tablet doesn't see the tablet.