title: Mousewheel scrolling on Infinite Scrolling EXTJS Grid isn't working
body: <p>we're using EXTJS 4.0.5 and having some issues with mousewheel scrolling.</p>
  
  <p>We've got a bunch of infinite scrolling grids that require the setting:</p>
  
  <p><code>verticalScrollerType: 'paginggridscroller'</code></p>
  
  <p>So we put this setting on a base class and had all grids inherit from this class. They all scroll fine and the infinite pagination works while you scroll, but the mouse wheel behaviour is off.</p>
  
  <p>Disabling this setting fixes mousewheel scrolling on the grids but obviously breaks the infinite scrolling pagination of the grid.</p>
  
  <p>The behaviour I'm seeing is the mousewheel will not scroll while the cursor is over the records in the grid, but will scroll if the cursor is over the scrollbar.</p>
  
  <p>Has anybody seen this issue before? I've found nothing in the documentation regarding mousewheel scrolling. Thanks.</p>