Creating a bottom window?

[Elena]

Hello,

how do you create a window as wide as its frame and positioned at the
bottom, no matter how many windows are there at the moment? I mean, a
window positioned like the `shrink-fit.el' in this picture:
http://www.emacswiki.org/emacs/DrewsEmacsWindowCallouts

I've checked the ELisp reference about windows, but it seems you can
just split existing windows.

Thanks.