The ability to add balloons through the Inventor API is unfortunately not available and it may be a while before Autodesk implements this capability. With a fundamental need for this feature I have developed a work-around to achieve balloon insertion via the API. The work-around involves an interactive approach to inserting balloons, is brief and easy to understand but fully customizable nonetheless. It also has the possibility of providing formatted text and many other key display characteristics. I have posted the solution including instructions for its use at:
http://www.melbtest.com.au/InventorAddBalloon/
Kind Regards
David Wilkie
