title: NSProgressIndicator can't set background color to white
body: <p>When I set my progress indicator's background to green, it works as expected.</p>
  
  <p><strong>Code</strong>:</p>
  
  <pre><code>loadingIndicator.wantsLayer = true
  loadingIndicator.layer?.backgroundColor = NSColor.greenColor().CGColor
  </code></pre>
  
  <p><strong>Result</strong>: </p>
  
  <p><a href="https://i.stack.imgur.com/5Cqlf.png" rel="noreferrer"><img src="https://i.stack.imgur.com/5Cqlf.png" alt="enter image description here"></a></p>
  
  <p>But when I set the background color to white, the background color stays gray (instead of changing to white).</p>
  
  <p><strong>Code</strong>:</p>
  
  <pre><code>loadingIndicator.wantsLayer = true
  loadingIndicator.layer?.backgroundColor = NSColor.whiteColor().CGColor
  </code></pre>
  
  <p><strong>Result</strong>:</p>
  
  <p><a href="https://i.stack.imgur.com/tJMlG.png" rel="noreferrer"><img src="https://i.stack.imgur.com/tJMlG.png" alt="enter image description here"></a></p>
  
  <p>Why does setting the background color to white not work, but green does? How can I correct this issue? I'm on OS X 10.11.4.</p>
  
  <p><strong>EDIT</strong>: This apparently only happens when the progress indicator is inside a view that was presented as a popover.</p>