title: Change appearance of a popover created using a popover segue in OS X
body: <p>I'm trying to use storyboards to build a simple app for Yosemite.  Creating a popover segue is easy - the segue is created from a button click to an <code>NSViewController</code> in my storyboard, and the Style is set to Popover.  This works great, but the trouble is, I'd like to change the appearance of this popover.  It seems to be defaulting to a Vibrant Dark appearance, but I'd like it to be Vibrant Light or Aqua.  I assume what is happening here is that behind the scenes, an <code>NSPopover</code> is being created to contain the view controller that I am displaying with my segue, but I can't figure out how to get access to this <code>NSPopover</code> object - the storyboard only gives me access to the view controller that I am displaying, and there isn't any <code>NSPopover</code> object available to use in interface builder. </p>
  
  <p>All I want to do is change the appearance of this popover I'm creating in my storyboard...Any suggestions?  Thanks!</p>