You can find the recording of the webinar where Bob and John talked about how to costumize MapInfo Pro using the .NET API here:
https://event.on24.com/eventRegistration/EventLobbyServlet?target=reg20.jsp&referrer=&eventid=1555310&sessionid=1&key=8F90B908B40D1E65A055893253EAA4AF®Tag=&sourcepage=register&cid=social_smm_mapinfo&cis=social_smm_ecomm
The slides and sample application from the webinar has been shared in the MapInfo Pro Developers group: The following link is no longer available. To access this information, copy the title found in the url into the search tool on the top nav bar, or try searching for key words in the post. https://li360.pitneybowes.com/s/relatedlist/0F9800000000QNyCAM/AttachedContentDocuments