[Haskell-cafe] WANTED: grey line layout boxes in vim and emacs

[Donald Bruce Stewart]

I'd like some more help from the editors in getting 2d layout right
without trying. Here's a mockup of vim with vertical grey bars
delimiting layout:

    http://www.cse.unsw.edu.au/~dons/tmp/haskell+boxes.png

Does anyone know how to get this effect in vim (or emacs)?

Bonus points if the grey bars are draggable, changing the indenting.
More bonus points for box-based navigation.

-- Don