[Xmonad] Switch screens less often?

[Kai Grossjohann]

I find that xmonad switches screens too often for my taste.  So I
would like to try out new behavior.  Has anyone implemented it
already?  If not, then I'd try to give it a go, but I don't know any
Haskell...

Specifically:

* Currently, Mod-1 and friends may switch screens if that workspace is
  already visible on another screen.

  I would like to make them beep instead, and not change workspaces.


* Currently, RotView switches screens when the next workspace in line
  is on another screen.

  I would like to make it skip such workspaces.
  
  Example: Say I am on screen 0, showing workspace 1.  Screen 1 shows
  workspace 3.  Then rotating to the right should show workspace 2,
  then workspace 4, skipping workspace 3.


* I would like to retain the behavior of Mod-w, Mod-e, Mod-r switching
  screens.


Kai