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 ?

'scripts and browser extensions. This may lead to subtle ' +
      'reconciliation issues. Try rendering into a container element created ' +
      'for your app.'
    );
    var nextWrappedElement = ReactElement(
      TopLevelWrapper,
      null,
      null,
      null,
      null,
      null,
      nextElement
    );
    var prevComponent = getTopLevelWrapperInContainer(container);
    if (prevComponent) {
      var prevWrappedElement = prevComponent._currentElement;
      var prevElement = prevWrappedElement.props;
      if (shouldUpdateReactComponent(prevElement, nextElement)) {
        var publicInst = prevComponent._renderedComponent.getPublicInstance();
        var updatedCallback = callback && function() {
          callback.call(publicInst);
        };
        ReactMount._updateRootComponent(
          prevComponent,
          nextWrappedElement,
          container,
          updatedCallback
        );
        return publicInst;
      } else {