I created in Studio a custom doc type inheriting from workspace. TemplateRoot has been configured as a possible container for this new doctype.

I can thus create such a doc under TemplateRoot. It does not appear in the template list on the workspace creation form, that seems quite logical. I would like to have the same behaviour made possible for my custom doctype : have a custom form based for the field of my doctype and a select widget listing templates.

How can I do such a thing in Studio or through configuration ?