title: NSTableView Highlight Colour when when table lose its focus
body: <p>I am using NSTableView in my project. When the user has clicked on a line, I use the standard blue selection colour. When the table lost it's focus, the selection colour changes to light grey colour.</p>
  
  <p>I am trying to keep the blue selection colour even the table looses it's focus.</p>
  
  <p>I've already tried overriding backgroundStyle of NSTableCellView and I can set custom colour when a cell is selected or not but the backgroundColor property is set to .light when the table lost it's focus.</p>