message: Collapsed navigation bar with sticky tabs
diff: import React, {useContext} from 'react';
  import {StyleSheet, SafeAreaView, Text, Image, FlatList, View, TouchableHighlight} from 'react-native';
  import {NavigationContext} from 'navigation-react';
  -import {NavigationBar, TabBar, TabBarItem} from 'navigation-react-native';
  +import {CoordinatorLayout, NavigationBar, TabBar, TabBarItem} from 'navigation-react-native';
  const Follow = ({account: {id, name, logo}}) => {
  const {stateNavigator} = useContext(NavigationContext);
  @@ -52,12 +52,16 @@ const Tweet = ({id, account: {id: accountId, name, logo}, text}) => {
  export default ({notifications}) => {
  return (
  <SafeAreaView style={{flex: 1}}>
  - <NavigationBar title="Notifications" barTintColor={Platform.OS === 'android' ? '#fff' : null} />
  + <CoordinatorLayout>
  + <NavigationBar title="Notifications" barTintColor={Platform.OS === 'android' ? '#fff' : null}>
  + <TabBar />
  + </NavigationBar>
  <TabBar segmented={true}>
  <TabBarItem title="All">
  <FlatList
  data={notifications}
  keyExtractor={(_item, index) => '' + index}
  + nestedScrollEnabled={true}
  style={styles.view}
  renderItem={({item}) => (
  item.follow ? <Follow {...item} /> : <Tweet {...item} />
  @@ -67,10 +71,12 @@ export default ({notifications}) => {
  <FlatList
  data={notifications.filter(({mention}) => mention)}
  keyExtractor={(_item, index) => '' + index}
  + nestedScrollEnabled={true}
  style={styles.view}
  renderItem={({item}) => <Tweet {...item} />} />
  </TabBarItem>
  </TabBar>
  + </CoordinatorLayout>
  </SafeAreaView>
  );
  };
  