In order to integrate a print functionality into edit-on Pro you could set up a custom action. To print the WYSIWYG content of the applet you could define a Javascript function e.g. print_wysiwyg() which requests the applet's source view content (getHTMLData / getStyleSheet etc. JavaScript APIs) and opens the content as HTML within a browser popup window which you can use to print the browser content.

You can find more information about defining JavaScript actions within the Integration Manual, Chapter 2. Advanced Integration, 1. Custom actions.