[xmonad] Grid layout eats other layouts

[Yitzchak Gale]

Using xmonad 0.7 and KDE 3.5 with the xmonad.hs
from http://haskell.org/haskellwiki/Xmonad/Using_xmonad_in_KDE

I want to add Grid to the default list of layouts.
When I do:

3a4
> import XMonad.Layout.Grid
10c11
<  , layoutHook            = avoidStruts $ layoutHook defaultConfig
---
>  , layoutHook            = avoidStruts $ layoutHook defaultConfig ||| Grid

I only get Tall and Grid. The last two layouts from
defaultConfig - Mirror Tall and Full - disappear,
seemingly "eaten" by Grid.

If I specify the entire layout list manually:

3a4
> import XMonad.Layout.Grid
10c11,12
<  , layoutHook            = avoidStruts $ layoutHook defaultConfig
---
>  , layoutHook            = avoidStruts $ let t = Tall 1 (3/100) (1/2) in
>                            t ||| Mirror t ||| Full ||| Grid

I get all four layouts as expected.

Any ideas why?

Thanks,
Yitz