title: Hide FAB in NestedScrollView when scrolling
body: <p>I am having a nestedscrollview with content like some linearlayouts and textviews.
  I am using a floatingactionbutton library for some reasons, as well. So I can't use any behavior for it.
  I don't know how I should handle the scrollchangelistener from scrollview to hide and show the fab dynamically like a behavior.</p>
  
  <p>Any suggestions how to hide and show the fab while scrolling?</p>