title: Draw shadow under NSImage
body: <p>Currently I'm drawing an NSImage in a custom NSCell like so:</p>
  
  <pre><code>- (void)drawInteriorWithFrame:(NSRect)theCellFrame inView:(NSView *)theControlView {
      // roundedCornerImage creates a new NSImage with rounded corners, rather than clipping.
      [[anIcon roundedCornerImage:5] drawInRect:anIconBox fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];
  }
  </code></pre>
  
  <p>Very simply I'm wondering how to draw an image underneath it. On the iPhone, I would do this by using: <code>CGContextSetShadow (currentContext, CGSizeMake(1, -1), 2)</code>; just before drawing the UIImage, but I'm unfamiliar with how to do it on the Mac.</p>
  
  <p>Any pointers would be great.</p>