code: public void hide(long duration, final AnimationListener listener) {
  		overlay.animate().alpha(0).setDuration(duration).setInterpolator(interpolator)
  				.setListener(new AnimatorListenerAdapter() {
  					@Override
  					public void onAnimationStart(Animator animation) {
  						if (listener != null) {
  							listener.onStart();
  						}
  					}
  
  					@Override
  					public void onAnimationEnd(Animator animation) {
  						overlay.setVisibility(View.GONE);
  						if (listener != null) {
  							listener.onEnd();
  						}
  					}
  				}).start();
  	}
docs: Hides the overlay.
  
  @param duration Duration of the animation in milliseconds. Use 0 for no animation.
  @param listener Listener for animation events.