Almost-identical metatile warning

[purrfectdoodle]

Let's say I make a signpost metatile on my primary set on the middle layer. Its bottom layer is grass or something. Now I have a secondary set that's got some special orange grass, and I put that same signpost in the secondary set on top of that orange grass. Then at some point I edit a pixel or two on the signpost on one of the two sets, but at this point I've forgotten about the identical signpost on the other set. I have no idea how easily doable a warning when two metatiles (16x16) are almost identical but not quite would be. A "hey are you sure this is intentional?" sort of thing.

[grunt-lucas]

It's very doable actually. There's this concept in text processing called Levenshtein distance. If I can come up with a clever way to represent a particular metatile layer as text, then I can probably use something like this to warn the user when it detects two tiles that are within a certain distance threshold, as that probably indicates a user mistake of some sort.