message: first active value highlight
diff: @@ -88,7 +88,7 @@ export default class DropdownMenu extends React.Component {
  let clonedMenuItems = menuItems;
  if (selectedKeys.length || firstActiveValue) {
  if (props.visible && !this.lastVisible) {
  - activeKeyProps.activeKey = selectedKeys[0];
  + activeKeyProps.activeKey = selectedKeys[0] || firstActiveValue;
  }
  let foundFirst = false;
  // set firstActiveItem via cloning menus
  