title: How to switch off screen on mac
body: <p>How could I switch off primary Macbook screen?
  I'm working with 2 External via Thunderbolt and HDMI on new Retina Macbook.</p>
  
  <p>I want to switch off retina display and work just with external monitors without closing the cover of my laptop. Is there any setup option for that? I didn't find it under Preferences.</p>