I want to write a handler to enable Visio add-in to intercept open / save GUI actions and offer additional data format for loading / storing diagrams. Is it possible to extend standard list of formats appearing in Visio dialog through API? Thank you.
You won't be able to make any changes to the open/close dialogs. That would be a huge security risk. Besides, the open/save dialogs are coded purely within Visio.
The only way will be to add your own dialog with your own open/save formats and add ribbon entries to suit..
@Paul, thank you. I suspected it is the case. Just wanted to be sure.