flutter - Subclass a class that extends StatelessWidget or StatefulWidget class

Question

Is it possible to create a class that extends a class extending StatelessWidget or StatefulWidget.

For example:

class MyButton extends StatelessWidget {
final String label;
Button({this.label});
@override
Widget build(BuildContext context) {
    return ButtonExample("label");}
}

then

class SubmitButton extends MyButton
{
   String label;
   SubmitButton({Key key, this.label}) : super(label: label);

// then somehow extend the parent build and change only the color
// or in case of StatefulWidget change a functionality
}

I tried to search for examples online but I had not success.

Answer 1

In Flutter composition is preferred over inheritance.
Widgets are not supposed to be extended, this is why there are no examples or tutorials how to do it.

Flutter has a strong focus on composition and the included widget library contains a lot of smaller widgets that do one thing well, that allow to compose them into custom widgets in many different ways.