WrapBackendScope.scala

class WrapBackendScope[P, S](b: BackendScope[P, S]){
  def props = CallbackTo[P](b.props)
  def state = CallbackTo[S](b.state)
  def both  = CallbackTo[(P, S)]((b.props, b.state))

  def modState(f: S => S, cb: Callback = Callback.empty): Callback =
    state >>= (s => b.setState(f(s), cb))

  def modStateCB(f: S => CallbackTo[S], cb: Callback = Callback.empty): Callback =
    state >>= (s => b.setStateCB(f(s), cb))
}