title: Cocoa bindings: combine fixed items with ArrayController bound items in an NSPopupButton
body: <p>I'm trying to make a color chooser using an NSPopupButton, and at the bottom i'd like a separator and a "Custom…" option. Is it possible to load the colors from array, then tack the separator and "custom" item on bottom? if so, how?</p>
  
  <p>Thanks!</p>