We created a low-level framework that was used by PDFKit (and hence by Preview) to change the way selection of text in PDF documents is done. We never worked on

We created a low-level framework that was used by PDFKit (and hence by Preview) to change the way selection of text in PDF documents is done. We never worked on Preview itself. Since the feature is part of PDFKit, it is also available to third-party apps that use PDFKit.