title: android fastScroll only covers part of the list
body: <p>I have a class which implements <code>expandable list activity</code>.<br>
  In the XML code (or I can do it in java), I set <code>fastScrollEnabled</code> to <code>true</code>. This does in deed enable fast scroll. BUT fast scroll only works in the top portion of the list. Like I can use the fastscroll thumb bar to scroll the whole list but only works in the top section of the scroll bar. It's not proportionate to the entire list. I can drag the thumb bar to the bottom of the list but it does no scrolling since the <code>listview</code> is already scrolled to the bottom due to the odd behaviour of it only working in the top portion of the list.<br>
  Confusing I know, I can try to clarify more if needed....</p>
  
  <p>I do implement a custom <code>BaseExpandableListAdapter.</code></p>