const store = Rx.Observable.create(function(observer) {

  let state = { userActions: {

    window: {

      leftPanelWidth: 300,

      backgroundColor: 0xffffff,

    }

  }};

  observer.next(state);

  state = { userActions: {

    window: {

      leftPanelWidth: 250,

      backgroundColor: 0xffffff,

    }

  }};

  observer.next(state);

  state = { userActions: {

    window: {

      leftPanelWidth: 250,

      backgroundColor: 0xff00ff,

    }

  }};

  observer.next(state);

});

​

​

const subscribe = store

  .map( state => state.userActions.window )

  .distinctUntilChanged( ( a, b ) => {

    return a.leftPanelWidth === b.leftPanelWidth && a.backgroundColor === b.backgroundColor

  })

  .subscribe(val => console.dir(val));

​

console.log( '--------------Done--------------' );