What could be improved

The different *Callbacks mixins should be configurable to allow for components to receive any events, regardless if they are "inside" the component or not; for example:

class FooComponent extends PositionComponent with TapCallbacks {
  @override
  void onTapDown(TapDownEvent event) {
    // only gets this if the click is inside the component (based on position & size)
  }

  // false by default; or some other name like this
  @override
  bool get receiveAllTapCallbacks => true;
}

Same for the other similar mixins.

Why should this be improved

Sometimes you want to listen to all events, so you can better organize logic within components and don't have to have things on the root level.

Any risks?

No.