[xmonad] Is this layout (with Tall) allowed?

[Maurí­cio]

This is my configuration file. Are parameters to Tall acceptable, as 
well as the double use of a single layout? (It builds and is usable, but 
sometimes things go wrong, like xmonad saying the focus is on firefox 
but everything I type going to emacs. Before trying to understand why, I 
would like to know if this configuration is supposed to work.) I'm using 
xmonad as it comes in latest Ubuntu.

Thanks for your thoughts,
Maurício

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import XMonad
import XMonad.Layout.Grid

main = xmonad $ defaultConfig {borderWidth=11, modMask=mod4Mask,
     normalBorderColor="#00ff00", focusFollowsMouse=False,
     layoutHook =((Tall 0 (1/100) (1/2)) ||| (Tall 1 (1/100)
     (9/10)))}
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