Estou tentando detectar um evento onFling para um objeto TextView. O código abaixo funciona perfeitamente para o evento onDown, mas falha ao obter os eventos onScroll ou onFling. Alguma dica?

Obrigad

package rob.testapp;

import android.app.Activity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity
{
    private GestureDetector myGestDetector;
    private TextView mainTextView;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        myGestDetector = new GestureDetector(this, new SimpleOnGestureListener()
        {
            @Override
            public boolean onScroll(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
            {
                mainTextView.setText("just scroll'n");
                return false;
            }

            @Override
            public boolean onDown(MotionEvent e1)
            {
                mainTextView.setText("on down");
                return false;
            }

            @Override
            public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY)
            {
                mainTextView.setText("on fling");
                return false;
            }
        });

        mainTextView = (TextView)findViewById(R.id.MainText);
        mainTextView.setText("Starting app...");
        mainTextView.setOnTouchListener(new View.OnTouchListener()
        {
            @Override
            public boolean onTouch(View v, MotionEvent event)
            {
                myGestDetector.onTouchEvent(event);
                return false;
            }
        });
    }
}

O layout é apenas um TextView dentro de um LinearLayou