@Anonymous, the difficulty here is not creating something that snaps to two points and then identifies where the middle is. That's easy enough. The challenge is teaching every tool in Revit to start using this capability when snapping. To implement this functionality, you're actually replacing one click with two clicks and those two clicks have very different behavior from the original clicks. So we essentially have to teach a lot of editors (and yes, we do reuse stuff, so it's not every single tool) to break out of what they're doing, do something else, and then go back to the original code as if there was only one click. It's hot a huge amount of work for each one, but it's a fairly large project when you include all of Revit's tools and the associated testing effort. Hope that helps.