title: Background color change in BottomNavigationView
body: <p>I have implemented <code>BottomNavigationView</code> which is available from the new support library 25.0.0. Here is my code for that</p>
  
  <pre><code>&lt;android.support.design.widget.BottomNavigationView
      android:id="@+id/bottom_navigation"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_alignParentBottom="true"
      app:itemBackground="@color/colorPrimary"
      app:itemIconTint="@drawable/text"
      app:itemTextColor="@drawable/text"
      app:menu="@menu/bottom_navigation_main" /&gt;
  </code></pre>
  
  <p>And <code>text.xml</code> drawable</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  &lt;selector xmlns:android="http://schemas.android.com/apk/res/android"&gt;
      &lt;item android:color="@android:color/white" android:state_enabled="true" /&gt;
      &lt;item android:color="@color/colorPrimaryDark" android:state_enabled="false" /&gt;
  &lt;/selector&gt;
  </code></pre>
  
  <p>With this code I am able to change text color when menu item is clicked, but when I apply same thing to <code>app:itemBackground</code> it is showing error <code>&lt;item&gt; tag requires a 'drawable' attribute or child tag defining a drawable</code>.</p>
  
  <p>This is what I have tried for <code>app:itemBackground</code></p>
  
  <pre><code>app:itemBackground="@drawable/text"
  </code></pre>
  
  <p>So my question is how can I change the background color of the selected menu item?</p>