Hey David,
Thanks for the patch. We already have a ticket for this, but I can't find it right now because our bug tracker seems to be down. When Trac comes back up, I'll find the ticket number so I can reference it in the commit and land your patch.
The plan is to add this now, deprecating all other positioning methods with the next major release. Then and after two major releases, we'll remove the code for the other positioning methods, greatly simplifying the implementation.