title: Toggle DataGridView row selection where SelectionMode is FullRowSelect
body: <p>I have a DataGridView where SelectionMode=FullRowSelect and MultiSelect=False.</p>
  
  <p>When a user clicks on a row it is selected as expected. However, clicking on the same row again does not deselect the row.</p>
  
  <p>How can the row selection be made to toggle between selected and unselected?</p>