public void animateVisibility(boolean visible) {
        if (mVisible != visible) {
            mVisible = visible;
            if (mAlphaAnimator != null) {
                mAlphaAnimator.cancel();
            }
            mAlphaAnimator = ObjectAnimator.ofFloat(this, "alpha", visible ? 1f : 0f);
            mAlphaAnimator.setDuration(visible ? 200 : 150);
            mAlphaAnimator.start();
        }
    }
Animates the visibility of the fast scroller popup.
android/third_party/recyclerview-fastscroll/src/main/java/com/simplecityapps/recyclerview_fastscroll/views/FastScrollPopup.java