title: Android Studio Theme editor not showing previews
body: <p>In Android Studio 1.5.1 my Theme Editor does not show previews for any theme I select.  </p>
  
  <p><a href="https://i.stack.imgur.com/Sc5NR.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/Sc5NR.jpg" alt="enter image description here"></a></p>
  
  <p>I've tried making a new project and see whats happening there, but it's still not showin any preview.</p>
  
  <p>I feel like I'm missing something silly.</p>