Choose a monitor
Open the Activities overview and start typing Wacom Tablet.
Click on Wacom Tablet to open the panel.
If no tablet is detected, you’ll be asked to Please plug in or turn on your Wacom tablet. Click the Bluetooth Settings link to connect a wireless tablet.
Click Map to Monitor…
Check Map to single monitor.
Next to Output, select the monitor you wish to receive input from your graphics tablet.
Only the monitors that are configured will be selectable.
Switch Keep aspect ratio (letterbox) to ON to match the drawing area of the tablet to the proportions of the monitor. This setting, also called force proportions, letterboxes the drawing area on a tablet to correspond more directly to a display. For example, a 4∶3 tablet would be mapped so that the drawing area would correspond to a widescreen display.