[xmonad] never show infobars on certain workspace

[Wirt Wolff]

Excerpts from enxt's message of Tue Dec 13 09:57:09 -0700 2011:
> 
> i'm looking for the method how to avoid showing infobars like dzenbar on a
> particular workspace. is it possible? if yes, could someone give concrete
> hints and recommendations how to implement it?
> 

There's an example at
http://www.haskell.org/pipermail/xmonad/2010-January/009552.html

If you want to be able to toggle the bar on sometimes but have it
default to off, in the example replace

  onWorkspace "vid" (Full ||| Grid)

with

  onWorkspace "vid" (avoidStrutsOn [] $ Full ||| Grid)

-- wmw