This is actually a tricky feature. Think about this: you are in an unbounded map, zoom waaaaaaaaay out, create a large area to copy. That's gonna take a huge amount of memory. And then transferring it, and saving it, that's gonna get ugly.
There might be some ways to optimize it, I'll need to digest it for a bit.
I'll put in a tracker so the request doesn't get lost.
I was thinking small areas and bound maps like in this example:
http://www.dundjinni.com/forums/forum_p ... PN=1&TPN=1
I would be able to copy a part of the altar and cover the sword that the party picked up. If the copy function is no good for you Trevor, a Clone Stamp Tool will do the same thing without your need to worry about a user copying too much.