 
 		// posting notification when zoomed, scrolled or resized
 		typealias T = RenderView
-		NotificationCenter.default.addObserver(self, selector: #selector(T.scrollContentDidChange(_:)),
-					name: NSNotification.Name.NSViewBoundsDidChange, object: nil)
+		NotificationCenter.default.addObserver(self, selector: #selector(T.scrollContentDidChange),
+					name: .NSViewBoundsDidChange, object: nil)
 		scrollView.allowsMagnification = true
 		scrollView.maxMagnification = 4
 		scrollView.minMagnification = 1

	}

	var drawingTransform: CGAffineTransform {
		guard let scene = self.scene else { return CGAffineTransform.identity }
		let targetRect = contentView.convert(self.contentView.bounds, to: self.mtkView)
		let transform0 = CGAffineTransform(translationX: 0, y: self.contentView.bounds.height).scaledBy(x: 1, y: -1)
		let transform1 = scene.bounds.transform(to: targetRect)

		self.bringSubview(toFront: self.drawView)
		self.bringSubview(toFront: self.scrollView)

        let contentSize = scene?.contentSize ?? bounds.size

        self.scrollView.documentView?.frame = CGRect(origin: .zero, size: contentSize)

		self.contentView.translatesAutoresizingMaskIntoConstraints = false
		self.contentView.autoresizingMask = [.viewMaxXMargin, /*.viewMinYMargin,*/ .viewMaxYMargin]
		self.setNeedsDisplay()
