title: Flutter BottomNavigationBar not working with more than three items
body: <p>I´ve a problem with the <strong>BottomNavigationBar</strong> in Flutter (0.6). As soon as I add <strong>more then three BottomNavigationBarItems</strong> as children, the buttons in the bar have <strong>white icons and they are messed up</strong>. When I use only three or less items, everything´s fine.</p>
  
  <p>Here´s the widget code I use and which breaks the bar:</p>
  
  <pre><code>bottomNavigationBar: BottomNavigationBar(
            currentIndex: 0,
            iconSize: 20.0,
            items: [
            BottomNavigationBarItem(
                title: Text('Home'), icon: Icon(Icons.accessibility)),
            BottomNavigationBarItem(
                title: Text('Preise'), icon: Icon(Icons.account_box)),
            BottomNavigationBarItem(
                title: Text('Test'), icon: Icon(Icons.adb)),
            BottomNavigationBarItem(
                title: Text('Mehr'), icon: Icon(Icons.menu))
          ])
  </code></pre>
  
  <p>Has anybody an idea what´s wrong here?</p>
  
  <p>Thanks in advance for any hint,
  Michael</p>