title: SplitView not layer-backed, but trying to use overlay sidebars
body: <p>This is my first time working with Cocoa, and I've added an NSSplitViewController as the content view of my NSWindowController. I added two side bars to the NSSplitViewController, but I keep getting the following <em>runtime</em> warning, and I can't seem to find anything about what is causing this:</p>
  
  <pre><code>WARNING: The SplitView is not layer-backed, but trying to use overlay sidebars..
  implicitly layer-backing for now. Please file a radar against this app if you see
  this.
  </code></pre>
  
  <p><strong>EDIT:</strong></p>
  
  <p>Everything is in Storyboards at this point. The NSSplitViewController has three sections, a left sidebar, and main content area, and a right sidebar (think Xcode or Pages). In both sidebars I have a single label (just for testing). Also, this is a <em>runtime</em> warning.</p>
  
  <p>Any insight on this would be great. Thanks!</p>