SUGGESTION: Adjustable size for the upper section in Collections

I would really wish that the horizontal dividing line in Collections was movable. The upper part takes up far too much space when the +/- sections are empty, when they're well filled, and when you just want to see as many books as possible -- while still being too small when you've put lots of things in +/- and need to see them all simultaneously.

Oh, and it would also be helpful if the Rule box automatically became as high as necessary (i e several lines) when active, so that one could always see the entire rule when working on it.