BeGraphic Pro used to have this feature in version 1.0 (only inside Excel by that time). As BeGraphic V2 is completely rebuilt from scratch (both for PowerPoint and/or Excel), we know that we have to put this function again in the new version.
So you can expect this function in less than 6 months if you buy the edition Pro. If you become a client who bought the Edition Pro, you could ask us to change the priorities (because we are listening to the users' requests).
Your need is not only important for clicking on a region to get details (figures, values, information...), it's also clever to add links between comments and their flags (e.g.: A, B, C, D, E...) on the chart http://www.google.com/finance?q=NASDAQ:AAPL