title: Textview can't be displayed on exoplayer videoview
body: <p>I want to make textview display on videoview，but the videoview is overwriting textview
  This is my xml code</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
  
  &lt;FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
  xmlns:app="http://schemas.android.com/apk/res-auto"
  android:layout_width="match_parent"
  android:layout_height="match_parent"&gt;
  
  &lt;TextView
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:text="Test"
      android:textSize="40sp" /&gt;
  
  &lt;com.devbrackets.android.exomedia.ui.widget.VideoView
      android:id="@+id/video_test"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      app:useDefaultControls="false"/&gt;
  &lt;/FrameLayout&gt;
  </code></pre>
  
  <p>and this is my mainactivity code</p>
  
  <pre><code>val videoView = findViewById&lt;VideoView&gt;(R.id.video_test)
                      videoView.setVideoURI(Uri.parse("${Source_add}"))
                      videoView.start()
  </code></pre>