     /// validate text size slider in touch bar
     @objc private func invalidateSlider(_ notification: Notification) {
         
-        guard
-            let scale = self.textView?.scale,
-            let item = self.item(forIdentifier: .textSizeSlider) as? NSSliderTouchBarItem
-            else { return }
+        guard let item = self.item(forIdentifier: .textSizeSlider) as? NSSliderTouchBarItem else { return }
         
-        item.slider.doubleValue = Double(scale)
+        item.slider.doubleValue = Double(self.textView.scale)
     }
     
 }

            
        case .textSizeSlider:
            let item = NSSliderTouchBarItem(identifier: identifier)
            item.slider.doubleValue = Double(self.textView?.scale ?? 1.0)
            item.slider.maxValue = Double(self.textView?.enclosingScrollView?.maxMagnification ?? 5.0)
            item.slider.minValue = Double(self.textView?.enclosingScrollView?.minMagnification ?? 0.2)
            item.minimumValueAccessory = NSSliderAccessory(image: #imageLiteral(resourceName: "SmallTextSizeTemplate"))
            item.maximumValueAccessory = NSSliderAccessory(image: #imageLiteral(resourceName: "LargeTextSizeTemplate"))
            item.target = self

    
    // MARK: Private Properties
    
    private var textView: NSTextView
    
    
    
