 
     // MARK: Window delegate
 
-    func windowWillClose(notification: NSNotification)
+    func windowWillClose(_ notification: Notification)
     {
         windowIsVisible = false
     }

    {
        super.windowDidLoad()

		println("PrinterController nib loaded")

    }

	override func awakeFromNib()

        outputLetters.stringValue = ""
        for letter in savedLetters
        {
            display(letter: letter)
        }
    }

	@IBAction func clearOutput(sender: Any)
	{
        letters = []
        redisplayLetters()
