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 ?

'componentDidUpdate instead.',
          owner.getName() || 'A component'
        );
        owner._warnedAboutRefsInRender = true;
      }
    }
    var internalInstance = ReactInstanceMap.get(publicInstance);
    if (internalInstance) {
      
      
      
      return !!internalInstance._renderedComponent;
    } else {
      return false;
    }
  },
  /**
   * Enqueue a callback that will be executed after all the pending updates
   * have processed.
   *
   * @param {ReactClass} publicInstance The instance to use as `this` context.
   * @param {?function} callback Called after state is updated.
   * @param {string} callerName Name of the calling function in the public API.
   * @internal
   */
  enqueueCallback: function(publicInstance, callback, callerName) {
    ReactUpdateQueue.validateCallback(callback, callerName);
    var internalInstance = getInternalInstanceReadyForUpdate(publicInstance);