The effect you are asking for could go right along with a piano that's out of regulation where the hammers are blocking against strings. I played an 1886 Chickering last week that had that issue in the bass with a couple of notes. The person just received it from a rebuilder and the instrument, while regulated otherwise, still had notes with that problem.

2. I just realized that right-clicking on a key has the same effect as left-clicking--it plays the note. I'm being partly tongue-in-cheek, here, by saying that this is a neglected part of the interface. On the other hand, could a right-click be exploited in some way?

--To play the note with default settings instead of whatever settings the user has changed, as a way to quickly compare the sound?
--To set split points for applying changes to parameters?

Sorry to suddenly be posting so many requests\suggestions. I should be working on a syllabus right now, and I'm seeking refuge in Pianoteq.