title: NSMattrix IBAction get selected radio
body: <p>I've put a NSMattrix on a NSWindow.
  This NSMattrix contains 2 radio buttons.</p>
  
  <p>I declared 3 IBOutlets:
  - One for the NSMattrix
  - One for each radio button (NSButtonCell).</p>
  
  <p>I declared 1 IBAction method: I've linked this same method on each radio button ant on the NSMattrix.
  This method is automatically called when i change the state o radio button. Great.
  But when i want to know the state of each radio button in this method, the state is not good.</p>
  
  <p>How should i do to get the state of each radio button in a event method ?</p>
  
  <p>Thanks</p>