Ideally, the clipboard should do it for you, and there should be a way to let it know that the files have been successfully pasted (or not, as the case may be). That would be my preferred solution, obviously...
But how would one go about it? There's nothing in the API that I could find
That's why I came up with the second idea; but even there, I can get items off the clipboard, but I can't find out where they were cut or copied. Creating a listener doesn't help much, a FlavorEvent simply tells you there is a new item on the clipboard, but not how it came to be there.