[xmonad] ppVisible with 3 screens

[Adam Vogt]

* On Friday, October 08 2010, Felix Blanke wrote:

>Hello,
>
>thanks a lot for your work!
>
>
>It works :) The short version
>
>"let prm (one:two:rest) = two:one:rest"
>
>is enough, because I only need to switch the first two elements.
>With this hack I don't need the colour thing.
>
>
>Thanks again!
>
>
>Regards,
>Felix

If you end up using that config with only one screen, that expression
will throw an exception. XMonad will most likely catch it, but the
recovery is to try again. Arguably xmonad should do something smarter,
but until something changes there, you'd get an infinite loop.

So add a fallback case to the definition:

] let prm (one:two:rest) = two:one:rest
]     prm x = x

--
Adam