message: add support for default tab
diff: @@ -3,6 +3,16 @@ import PropTypes from "prop-types";
  import "./style.css";
  export default class VerticalTabbar extends React.Component {
  + constructor(props) {
  + super(props);
  + this.state = {
  + activeTab: props.defaultTab ? {
  + tab: props.defaultTab
  + } : {
  + tab: props.tabs[0]
  + }
  + };
  + }
  static propTypes = {
  children: PropTypes.node,
  tabs: PropTypes.array.isRequired,
  