Manually Control What Appears in "Current Sprint"

I did a search and was surprised not to see this topic already going, so forgive me if this is a duplicate. It's related to this issue (but different):

http://getsatisfaction.com/pivotal/to...

We're finding it annoying that our current sprint can span 3 columns -- Completed, Current, and Backlog. We are using Releases to designate when it starts/stops, but that is a hack at best. Would be good to have a mechanism to be able to show "current sprint" and have that reflect everything that is actually committed to by engineering -- the automatic shifting based on Velocity makes sense for planning purposes, but day-to-day that isn't always accurate enough to reflect reality (and is especially hard to stomach for one's first few sprints using pivotal when your velocity isn't accurate anyway).

Perhaps being able to click on a given release and show everything above it in a single column?

Or, perhaps being able to select a specific story and mark it as the "bottom" of the Current (and/or use that story to override the Velocity?).

Or, letting us override the start/end dates for a Sprint, so that if we have an odd sprint we don't end up messing up all future Sprints?