A developer just ran into an issue with OnFileResolution when handled inside an application using Inventor Apprentice. No matter what value they set the FullFileName parameter to, it got ignored.
Wayne already blogged about running into issues with events, but I've only experienced it in a way that the event was not caught at all. This time it is caught but the parameter change has no effect. The same trick helps here too though: make sure that Embed Interop Types is set to False.