title: How can I overlay a background color over an NSVisualEffectView and use vibrant controls?
body: <p>I want to use <code>NSVisualEffectView</code> with dark vibrancy, but I find the effect too pale in some situations, so I'd like to darken the background.</p>
  
  <p>Here is an example app, using <code>NSBox</code> views to provide a darker background.</p>
  
  <p><img src="https://i.stack.imgur.com/RMEmj.png" alt="enter image description here"></p>
  
  <p>We can see that the <code>NSBox</code> 'primary' appearance manages to overlay the background and the button happily sits on top of that. However, on the <code>NSBox</code> with custom appearance, the button appears to 'cut' through the background to the visual effect view beneath. </p>
  
  <p>I've tried subclassing <code>NSVisualEffectView</code> and overriding <code>-drawRect:</code> to fill it with a different color and the result is the same.</p>
  
  <p>Is there a way to overlay vibrant controls over other views?</p>