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 ?

delete instancesByReactRootID[prevComponent._instance.rootID];
    ReactUpdates.batchedUpdates(
      unmountComponentFromNode,
      prevComponent,
      container,
      false
    );
    return true;
  },
  _mountImageIntoNode: function(
    markup,
    container,
    instance,
    shouldReuseMarkup,
    transaction
  ) {
    invariant(
      container && (
        container.nodeType === ELEMENT_NODE_TYPE ||
        container.nodeType === DOC_NODE_TYPE ||
        container.nodeType === DOCUMENT_FRAGMENT_NODE_TYPE
      ),
      'mountComponentIntoNode(...): Target container is not valid.'
    );
    if (shouldReuseMarkup) {
      var rootElement = getReactRootElementInContainer(container);
      if (ReactMarkupChecksum.canReuseMarkup(markup, rootElement)) {
        ReactDOMComponentTree.precacheNode(instance, rootElement);
        return;
      } else {