Fix broken visuals when re-arranging cells

[TimOliver]

When re-arranging cells in edit mode, the cells don't update whether their corners need to be appropriately rounded or not.

This should be relatively easy to fix, but it will require stepping through how the cell views are manipulated during the drag (Reveal will make this really easy though. :)

I'll keep this issue open about it for now, and if and when I need this logic in my production code, I'll revisit it.