title: How to get scroll position from GridView?
body: <p>I am trying to build my own grid view functions - extending on the <code>GridView</code>.
  The only thing I cannot solve is how to get the current scroll position of the <code>GridView</code>.</p>
  
  <p><code>getScrollY()</code> does always return 0, and the <code>onScrollListener</code>'s parameters are just a range of visible child views, not the actual scroll position.</p>
  
  <p>This does not seem very difficult, but I just can't find a solution in the web.</p>
  
  <p>Anybody here who have an idea?</p>