const { observable } = mobx;

const { observer } = mobxReact;

const { Component } = React;

​

@observer 

class ParentComponent extends Component {

  @observable isBusy = false;

​

  handleBusy = () => {

    this.isBusy = true;

  }

​

  render() {

    const { isBusy, handleBusy } = this;

    return <div>

      <ChildComponent onClick={handleBusy}/>

      <button disabled={isBusy}> Parent Button </button>

    </div>;

  }

}

​

@observer 

class ChildComponent extends Component {

  render() {

    const { onClick } = this.props;

    return <div>

      <button onClick={onClick}> Child Button </button>

    </div>;

  }

}

​

ReactDOM.render(

  <ParentComponent />,

  document.getElementById('app')

);