A layout which gives each window a specified amount of screen space relative to the others. Compared to the Mosaic layout, this one divides the space in a more balanced way.

You can use this module with the following in your xmonad.hs:

import XMonad.Layout.MosaicAlt
import qualified Data.Map as M

Then edit your layoutHook by adding the MosaicAlt layout:

myLayout = MosaicAlt M.empty ||| Full ||| etc..
main = xmonad def { layoutHook = myLayout }

For more detailed instructions on editing the layoutHook see the tutorial and XMonad.Doc.Extending.

In the key-bindings, do something like:

    , ((modm .|. shiftMask  , xK_a    ), withFocused (sendMessage . expandWindowAlt))
    , ((modm .|. shiftMask  , xK_z    ), withFocused (sendMessage . shrinkWindowAlt))
    , ((modm .|. shiftMask  , xK_s    ), withFocused (sendMessage . tallWindowAlt))
    , ((modm .|. shiftMask  , xK_d    ), withFocused (sendMessage . wideWindowAlt))
    , ((modm .|. controlMask, xK_space), sendMessage resetAlt)
    ...

For detailed instruction on editing the key binding see:

the tutorial.