Drawing into the fullscreen

[Tim Hall]

How is it possible to draw into the whole screen even though the
window you have opened is smaller than the whole screen?  I don't
care if I'm drawing over other windows.  (Actually I'm using 
overlays so it doesn't matter)  I tried screenspace( ) and that
didn't do it.  I tried the viewport/ortho2 that screenspace( )
is supposed to do and that didn't do it. In both cases when what
it is that I'm drawing is in my window it shows up, but never shows
up outside my window.

Thanks
-Tim Hall

"Severance, The birds of leaving call to us, yet here we stand
endowed with the fear of flight" -Dead Can Dance