How to tell when the last row of a dxGrid:GridControl becomes visible?

With a GridControl, how can I trigger an event when the last row of the list becomes visible?

I'm using a GridControl to display a list of data and check boxes, and I want to trigger an event when the user scrolls down far enough for the last row of data to become visible, but I'm having trouble figuring out how to do it. Can someone please point me in the right direction? This is how I'm declaring my list:

<dxGrid:GridControl x:Name="dxDataList" ItemsSource="{Binding myDataList}">
      <dxGrid:GridControl.Columns>
          <dxGrid:SwitchColumn FieldName="bIsChecked" Caption="Completed"/>
          <dxGrid:TextColumn FieldName="CheckBoxText" Caption="Task"/>
      </dxGrid:GridControl.Columns>
</dxGrid:GridControl>