title: DataGrids over ScrollViewer prevent it to scroll
body: <p>I have multiples DataGrids disposed over a ScrollViewer.
  These DataGrids have an "height: auto" property so that I can hide the scrollbar and view all the content.
  The only problem is that the DataGrids takes the focus and so I can't scroll the ScrollViewer.
  Is that a property to keep the focus on the ScrollViewer but also keeping the behaviour of the DataGrids (so I can select elements) ?</p>
  
  <p>Thank you !</p>