Python ebook maker 3 - Save files

Python & tkinter ebook maker: How to save the changes you do in the various chapters contained if different text files. We are going on with our little project about making a notepad. Now our aim is to save the changes in the different files from the app, as, until now, we were only able to read the files. Another step to the final target of our simple example of app to use tkinter for a real app.
For more details go to my blog post in the link below: