title: How to keep single checkableBehavior mode in drawer menu for NavigationView when we add section?
body: <p>I try to implement a drawer with new component of material design : <a href="https://developer.android.com/reference/android/support/design/widget/NavigationView.html" rel="noreferrer">NavigationView</a>.</p>
  
  <p>It's work very well. When I select an item changes its color change well with <code>android:checkableBehavior="single"</code>.</p>
  
  <pre><code>&lt;group
      android:checkableBehavior="single"&gt;
  
      &lt;item
          android:id="@+id/drawer_home"
          android:checked="true"
          android:icon="@drawable/ic_home_black_24dp"
          android:title="@string/home"/&gt;
  
      &lt;item
          android:id="@+id/drawer_favourite"
          android:icon="@drawable/ic_favorite_black_24dp"
          android:title="@string/favourite"/&gt;
      ...
  
      &lt;item
          android:id="@+id/drawer_settings"
          android:icon="@drawable/ic_settings_black_24dp"
          android:title="@string/settings"/&gt;
  
  &lt;/group&gt;
  </code></pre>
  
  <p>The problem come when I try to use section in drawer. It's this case, I can't use <code>android:checkableBehavior="single"</code> and I lost the color change in the selection of an item.</p>
  
  <pre><code>&lt;item
      android:id="@+id/section"
      android:title="@string/section_title"&gt;
  
      &lt;menu&gt;
          &lt;item
              android:id="@+id/drawer_favourite"
              android:icon="@drawable/ic_favorite_black_24dp"
              android:title="@string/favourite"/&gt;
  
          &lt;item
              android:id="@+id/drawer_downloaded"
              android:icon="@drawable/ic_file_download_black_24dp"
              android:title="@string/downloaded"/&gt;
      &lt;/menu&gt;
  
  &lt;/item&gt;
  </code></pre>