title: Button is behind the ListView in FrameLayout
body: <p>I have a FrameLayout that consists of a list view and a button. The whole point of the FrameLayout is that elements that are after other elements will be displayed above them.     </p>
  
  <p>Since the button code is below the ListView code, I expected the button will always be on top, but it isn't. I can't figure it out - as soon as I get enough items in my list, the button is underneath it and it becomes obsolete.  </p>
  
  <p><strong>XML:</strong></p>
  
  <pre><code>&lt;FrameLayout
      android:id="@+id/content_frame"
      android:layout_width="match_parent"
      android:layout_height="match_parent" &gt;
  
      &lt;ListView
          android:id="@+id/lvMovies"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_marginBottom="8dp"
          android:background="#fff"
          android:elevation="3dp"
          android:paddingTop="8dp" /&gt;
  
      &lt;Button
          android:id="@+id/btnAddMovie"
          android:layout_width="60dp"
          android:layout_height="60dp"
          android:layout_gravity="bottom|end"
          android:layout_marginBottom="16dp"
          android:layout_marginEnd="16dp"
          android:layout_marginRight="16dp"
          android:background="@drawable/raised_action_button"
          android:elevation="5dp"
          android:fontFamily="sans-serif-light"
          android:gravity="center"
          android:text="+"
          android:textColor="#ffffff"
          android:textSize="30sp" /&gt;
  &lt;/FrameLayout&gt;
  </code></pre>