title: Cocoa binding to a particular item in an array controller
body: <p>Is it possible using <code>NSArrayController</code> to bind a <code>NSTextField</code>'s value to a particular item in the array?  In particular, I want to bind to a property on the first item in the array, and show nothing if the array is empty.</p>
  
  <p>Using <code>arrangedObjects.command</code> shows just "(" -- presumably it's trying to show a multi-line string with comma-separated strings for each item.  I just want the first one.</p>