title: Android set anchor to Bottom Sheets
body: <p>I wanna set an anchor to my Bottom Sheet:   </p>
  
  <pre><code>&lt;!-- bottom sheets --&gt;
  &lt;LinearLayout
      android:id="@+id/bottom_sheet"
      android:layout_width="match_parent"
      android:layout_height="300dp"
      android:orientation="vertical"
      android:padding="10dp"
      app:layout_behavior="@string/bottom_sheet_behavior"&gt;
  
      &lt;TextView
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:text="bottom sheets test! " /&gt;
  
      &lt;TextView
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_marginTop="20dp"
          android:text="bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! bottom sheets content! " /&gt;
  &lt;/LinearLayout&gt;
  
  &lt;android.support.design.widget.FloatingActionButton
      android:id="@+id/fab"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_margin="@dimen/fab_margin"
      android:src="@android:drawable/ic_dialog_email"
      app:layout_anchor="@id/bottom_sheet"
      app:layout_anchorGravity="bottom|end" /&gt;
  </code></pre>
  
  <p>    </p>
  
  <p>I add the FAB as the direct child of the CoordinateLayout and set the bottom sheet's id to the FAB's layout_anchor and set its layout_anchorGravity. But it doesn't work.The FAB won't move.</p>