title: Programmatically deselect a row in a DataGrid
body: <p>I'm struggling to find a solution to this. </p>
  
  <p>What I am trying to do is to only make certain rows selectable in a DataGrid. The SelectionMode is FullRow. An example would be if a user tried to drag-select a few rows, and one of them I wouldn't want to be selectable. In this instance I would want the valid rows to be selected still, but not the invalid one.</p>
  
  <p>Any ideas?</p>