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Borodin - first up,
If you want to do any serious development with the core then I think you should liaise with Kovid, otherwise you may enter on a path that he's a week away from exiting because its code complete
As well the PI Wish List there are a number of PI's written by kiwidude. He is currently unavailable to spend time maintaining/enhancing them them due other commitments. There are outstanding 'defects' and enhancement requests with a few of them - Find Duplicates & Modify come to mind, and I'd like View Manager to have an option to integrate with Virtual Libraries.
That could be another starting point, I can guarantee you'd get a slew of thanks, kisses, hugs and immeasurable quantities of karma.
BR