How to use subclass of a control

If making subclass of a control, say Canvas subclass. Then how do you drag in the subclass of the control ?

(Or if putting Canvas on the designer, then how do you set the Canvas super to the Subclass)

I was not able to find any way to use the subclass.

Thanks

Björn

Yeah that's a daft UX bug on my part. Sorry. Fixed for the next release: https://feedback.objo.dev/bug/95