title: MobX action transfer to function as callback
body: <p>Question:</p>
  
  <p>if I have store (pseudo code)</p>
  
  <pre><code>export default class MainStore {
    @observable someObservable = [];
  
    someFuncWithApi(actionFuncFromComponent) {
      apiCall.then(res =&gt; actionFuncFromComponent(res.loadPercentage)).then(() =&gt; ....)
    }
  }
  
  const mainStore = new MainStore;
  
  ....
  
  @inject('mainStore')
  @observer
  export default class SomeComponent extends Component {
    @observable percentage = null;
  
    @action
    setPercentage(percentage) {
      this.percentage = percentage
    }
  
    someHandle() {
      this.props.mainStore.someFuncWithApi(this.setPercentage)
    }
  }
  </code></pre>
  
  <p>This need for changing load percentage, someFuncWithApi is called but not change percentage or rerender in component. Please, tell me the right way for this.</p>