Android : Positionning the MediaController with setAnchorView

Question

Since 24 hours I'm trying to set the Anchor view of my MediaControler without success.

My VideoView is embedded in a bigger application but even with a very simple testing app I don't understand the problem.

Here is the code of the onCreate of my testing activity :

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);



final VideoView vv = (VideoView) findViewById(R.id.videoView1);
vv.setVideoURI(Uri.parse("http://192.168.30.188/test.mp4"));

final MediaController mediaController = new MediaController(ll.getContext());
vv.setMediaController(mediaController);                     

vv.setOnPreparedListener(new OnPreparedListener() {

    @Override
    public void onPrepared(MediaPlayer mp) {
        mediaController.setAnchorView(vv);
    }
});

vv.requestFocus();

}

And here is my simple layout :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >


        <FrameLayout
            android:id="@+id/layout1"

            android:layout_width="218dp"
            android:layout_height="162dp"
            android:background="@android:color/holo_purple">

        <VideoView
            android:id="@+id/videoView1"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

        </FrameLayout>

</RelativeLayout>

It seems that the media controller appears aligned with the bottom of my video view, but ever horitzontally centered !!!

I had a look at a lot of stack overflow "solutions" (more or less good) or other site samples and I can't understand ...

Can anybody help me please ?