Module concrete 

The same trait for the toolkit’s own decorators that apps box (concrete_decorator_widget): it has no blanket Widget impl, so each such type gets a concrete one, compiled once into the toolkit. Through the blanket impl a decorator’s Widget methods are generic, and every app that boxes one compiled them again, with the inner widget they forward to.

Traits

Decorator

A widget that extends another by overriding a few Widget methods and forwarding the rest. See the module docs.