/*------------------------------------------------------------------*\
   howto change to active screen with the keyboard? 
\*------------------------------------------------------------------*/

  what to achieve?

    you are on localhost:0.0 with your mouse and want to change it
    with a keybinding to localhost:0.1 

  solution:

    install xwit (http://www.x.org/contrib/utilities/xwit-3.4.README)
    and bind a key to

      export DISPLAY=:0.1; xwit -warp 100 100

    to swap back?

      export DISPLAY=:0.0; xwit -warp 100 100