title: RecyclerView with items of different height: Scrollbar
body: <p>I have a <code>RecyclerView</code> with items of varying heights with a scrollbar. 
  Because of the different heights of the items, the scrollbar changes it's vertical size, dependent on which items are currently displayed (see screenshots). 
  I have created an example project that displays the problem <a href="https://github.com/fweigl/ScrollbarExample" rel="noreferrer">here</a>. </p>
  
  <ol>
  <li>Has anyone had the same problem and fixed it?</li>
  <li>How can I override the calculation of the scrollbar height and position to come up with an own implementation?</li>
  </ol>
  
  <p><strong>EDIT:</strong> The scrollbar's position and height can be controlled by overriding <code>RecyclerViews</code> <code>computeVerticalScrollOffset</code>, <code>computeVerticalScrollRange</code> and <code>computeVerticalScrollExtent</code>.
  I have no idea though on how to implement these to make the scrollbar work properly with dynamic item heights. </p>
  
  <p>The problem, I reckon, is that <code>RecyclerView</code> estimates the total height of all items based on the items currently visible and sets position and height of the scrollbar accordingly. One way to solve this might be to give a better estimation of the total height of all items. </p>
  
  <p><a href="https://i.stack.imgur.com/zdUg4m.png" rel="noreferrer"><img src="https://i.stack.imgur.com/zdUg4m.png" alt="large scrollbar"></a>
  <a href="https://i.stack.imgur.com/TCg9om.png" rel="noreferrer"><img src="https://i.stack.imgur.com/TCg9om.png" alt="small scrollbar"></a></p>