anchor.diff:  
       if (_body == null)
         return;
  -    for(box2d.Fixture f = _body.getFixtureList(); f != null; f = f.getNext()) {
  +    for (box2d.Fixture f = _body.getFixtureList(); f != null; f = f.getNext()) {
         f.setSensor(isSensor);
       }
     }
   
  -  Offset linearVelocity;
  -  double angularVelocity;
  -
  -  double linearDampening;
  -
  -  double angularDampening;
  +  Offset _linearVelocity;
  +
  +  Offset get linearVelocity {
  +    if (_body == null)
  +      return _linearVelocity;
  +    else {
  +      double dx = _body.linearVelocity.x * _physicsNode.b2WorldToNodeConversionFactor;
  +      double dy = _body.linearVelocity.y * _physicsNode.b2WorldToNodeConversionFactor;
  +      return new Offset(dx, dy);
  +    }
  +  }
  +
  +  set linearVelocity(Offset linearVelocity) {
  +    _linearVelocity = linearVelocity;
  +
  +    if (_body != null) {
  +      Vector2 vec = new Vector2(
  +        linearVelocity.dx / _physicsNode.b2WorldToNodeConversionFactor,
  +        linearVelocity.dy / _physicsNode.b2WorldToNodeConversionFactor
  +      );
  +      _body.linearVelocity = vec;
  +    }
  +  }
  +
  +  double _angularVelocity;
  +
  +  double get angularVelocity {
  +    if (_body == null)
  +      return _angularVelocity;
  +    else
  +      return _body.angularVelocity;
  +  }
  +
  +  set angularVelocity(double angularVelocity) {
  +    _angularVelocity = angularVelocity;
  +
  +    if (_body != null) {
  +      _body.angularVelocity = angularVelocity;
  +    }
  +  }
  +
  +  // TODO: Should this be editable in box2d.Body ?
  +  final double linearDampening;
  +
  +  double _angularDampening;
  +
  +  double get angularDampening => _angularDampening;
  +
  +  set angularDampening(double angularDampening) {
  +    _angularDampening = angularDampening;
  +
  +    if (_body != null)
  +      _body.angularDamping = angularDampening;
  +  }
   
     bool allowSleep;
   
  
positive.code:     this.friction = friction;
      this.restitution = restitution;
      this.isSensor = isSensor;
    }
  
    Object tag;
  
    PhysicsShape shape;
  
    PhysicsBodyType type;
  
  
negative.code:     double friction: 0.0,
      double restitution: 0.0,
      bool isSensor: false,
      Offset linearVelocity: Offset.zero,
      double angularVelocity: 0.0,
      this.linearDampening: 0.0,
      double awakeangularDampening: 0.0,
      this.allowSleep: true,
      this.awake: true,
      this.fixedRotation: false,
  