I use `ReactDOM.unstable_renderSubtreeIntoContainer` to render a portal.

``` javascript
class Modal extends React.Component {

componentDidMount() {
    this.node = document.createElement('div');
    document.body.appendChild(this.node);
    this.renderPortal(this.props);
}

componentWillReceiveProps(nextProps) {
    this.renderPortal(nextProps);
}

componentWillUnmount() {
    ReactDOM.unmountComponentAtNode(this.node);
    document.body.removeChild(this.node);
}

renderPortal = (props) => {
    renderSubtreeIntoContainer(this, <ModalPortal {...props} />, this.node);
}

render() {
    return null;
  }
}
```

In my root component:

``` javascript
class App extends React.Component {
    static childContextTypes = {
        highlightColor: React.PropTypes.object
    }

    getChildContext() {
        return {
            highlightColor: this.props.highlightColor
        }
    }

    ...
}
```

The context of root component will be updated and passed to children if  `this.props.highlightColor` is changed. This is right.
I can access the correct context in the `<ModalPortal/>` component in the first render.
And after that the context passed to  `<ModalPortal/>` **does not change any more** when the context of root component changed.
But I can access the correct context in the `<Modal/>`  every render.

what's wrong with my code ?

if (prevComponent) {
      var prevWrappedElement = prevComponent._currentElement;
      var prevElement = prevWrappedElement.props;
      if (shouldUpdateReactComponent(prevElement, nextElement)) {
        ReactUpdateQueue.enqueueElementInternal(prevComponent, nextWrappedElement);
        if (callback) {
          ReactUpdateQueue.enqueueCallbackInternal(prevComponent, callback);
        }
        return prevComponent;
      } else {
        ReactNativeMount.unmountComponentAtNode(containerTag);
      }
    }
    if (!ReactNativeTagHandles.reactTagIsNativeTopRootID(containerTag)) {
      console.error('You cannot render into anything but a top root');
      return null;
    }
    ReactNativeTagHandles.assertRootTag(containerTag);
    var instance = instantiateReactComponent(nextWrappedElement);
    ReactNativeMount._instancesByContainerID[containerTag] = instance;
    if (__DEV__) {
      
      
      instance._debugID = 0;