<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:id="@+id/l1"
android:layout_height="fill_parent"
tools:context=".OverlayActivity" >

<Button
    android:id="@+id/mainButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textAlignment="center"
    android:gravity="center_vertical"
    android:layout_alignParentRight="true"
    android:layout_centerInParent="true"
    android:clickable="true"
    android:visibility="visible"
    android:focusable="true">

</Button>

@Override
public void onCreate() {
    super.onCreate();
    LayoutInflater layoutInflater = (LayoutInflater) getSystemService(LAYOUT_INFLATER_SERVICE);
    View oView = layoutInflater.inflate(R.layout.activity_overlay, null);
    WindowManager.LayoutParams params = new WindowManager.LayoutParams(
            WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
            0 | WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
            PixelFormat.TRANSLUCENT);
             WindowManager.LayoutParams.TYPE_PHONE,
             WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH,
             PixelFormat.TRANSLUCENT);
    WindowManager wm = (WindowManager) getSystemService(WINDOW_SERVICE);
    wm.addView(oView, params);
    Button button = (Button)oView.findViewById(R.id.mainButton);


    button.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View arg0) {

           Toast.makeText(OverlayService.this, "GotCha!!! ", Toast.LENGTH_LONG).show();

        }

    });
    ViewGroup vg = (ViewGroup)oView.findViewById(R.id.l1);
    final Display  metrics = ((WindowManager) getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
    vg.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
       switch(event.getActionMasked()){

            case MotionEvent.ACTION_MOVE:
             int x = (int)event.getX() - offset_x;
             int y = (int)event.getY() - offset_y;


             int w = metrics.getWidth()-100;
             int h = metrics.getHeight()-100;

             if(x > w){
                x = w;
             }
             if(y > h){
                y = h;
             }
             LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
             new ViewGroup.MarginLayoutParams(
             LinearLayout.LayoutParams.WRAP_CONTENT,
             LinearLayout.LayoutParams.WRAP_CONTENT));
             lp.setMargins(x, y, 0, 0);
             selected_item.setLayoutParams(lp);
             break;

             default:
             break;
        }
        return true;
    }
});
    button.setOnTouchListener(new View.OnTouchListener() {
    @Override
    public boolean onTouch(View v, MotionEvent event) {
       switch(event.getActionMasked()){
            case MotionEvent.ACTION_DOWN:
                offset_x = (int)event.getX();
                offset_y = (int)event.getY();
                selected_item = v;
                break;
                default:
                    break;
       }
       return false;
    }
    });
}