I don't disagree. I think the work to get it right is a little non-trivial, is in dygraph-tickers. The fundamental problem is that the the options view doesn't know whether the label formatter it's using is actually a default formatter or one specified by options. (There's also some burned CPU cycles because in this case, even though it eventually returns "1K" it still calls the custom formatter first (and then tries to figure out if it's a multiple of 1000.

Here's my suggestion, if you're game: accept this pull request (at the very least, it documents existing behavior.) I assigned bug 414 to you since you know dygraph-tickers better than me (assuming you would either mark it fixed, or push back, [you chose the latter.]) Would you then take a shot at it - see if it's something you can easily fix? If not, I further suggest we mark this as existing v1 behavior and deal with it in v2, where we can rewrite this stuff a bit.