: You can add one via [Layer] menu > [New Layer] > [Paper] and select a background color.
Limitations
If CSP X launches, Celsys may follow Autodesk’s model—no more perpetual licenses. The "X" version could be exclusive to the "Monthly Plan" or a new "Ultimate" tier costing $11.99/month (up from $8.99 for EX). clip studio paint x