         redisplayLetters()
     }
 
-    override func showWindow(sender: AnyObject?)
+    override func showWindow(_ sender: Any?)
     {
         super.showWindow(sender)
         windowIsVisible = true

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

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

    {
        super.windowDidLoad()

		print("PrinterController nib loaded")
    }

	override func awakeFromNib()
