[xmonad] new grid layout

[Brian Lewis]

Hi. I'm switching to xmonad from ion. It's really cool.

I used to split my ion desktops once vertically. Then I'd split each
half horizontally. So I'd have 4 same-sized rectangular panes. I used
the vi keys hjkl to focus the one I wanted. There was no main window,
there was no stack.

I'd like an xmonad layout that worked sort of the same way. You'd
add/delete columns and rows. In this way, you'd always have a grid, so
no matter which rectangle had focus, it'd be easy to decide which
should have focus after any of the four possible movements.

For example, an 'empty' desktop has 1 column, 1 row. Adding a row
splits it horizontally, so now there are 2 panes. Adding another row
results in the desktop being split twice horizontally, dividing it
into three parts. Adding a column splits it horizontally, resulting in
6 panes. The panes aren't all necessarily the same size; I don't know
the correct way to state mathematically the type of partitioning this
is.

I find that focus model to be way more intuitive than wmii-style
up/down. Also, stuff like remote irssis in other panes aren't forced
to resize themselves just because I get rid of some other application.
For example, if I close a browser in the left column of a 2-column,
1-row desktop, the left column just becomes empty. Nothing resizes.

But I don't know if xmonad even likes the idea of empty panes. I'm
just starting to learn Haskell; I'm really not up to coding a new
layout right now. Someone save me? Thanks.