[xmonad] XMonad can't support _NET_ACTIVE_WINDOW" root window property.

[Andy Stewart]

Hi, develop team!

I have use XMonad some month.
It's great, thanks!

But i found XMonad does not support the necessary root window property,
namely "_NET_ACTIVE_WINDOW".

Because i have a emacs extension for SCIM-Bridge need use this root
window property to compute input focus position.

And can use command "xprop -root _NET_ACTIVE_WINDOW" to test this
problem, will got "_NET_ACTIVE_WINDOW:  no such atom on any window."
message.

But in GNOME, this command will get value of "_NET_ACTIVE_WINDOW".

So please add this root window property in XMonad.

Thanks!

  -- Andy.