     
     // MARK: - PopoverTableViewController Presentation
 
+    // iOS Popover presentation Segue
+    // http://sunnycyk.com/2015/08/ios-popover-presentation-segue/
     override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
         if (segue.identifier == "PopoverSettings") {
             if let popopverVC: PopoverTableViewController = segue.destination as? PopoverTableViewController {

        for view in pdfView.subviews {
            if view.isKind(of: UIScrollView.self) {
                (view as? UIScrollView)?.scrollsToTop = false
            }
        }
        

                    } else {
                        pdfView.displayDirection = .vertical
                    }
                    isVerticalWriting = vertically
                }
                
                if rightToLeft != isRightToLeft {
