Script

#!/bin/sh
# spawn a new terminal window inside a drawn rectangle
# edit the part with urxvt to match your terminal

set -e

wglyph=7        # glyph width, in pixels
hglyph=16       # glyph height, in pixels
border=20        # border width, in pixels
title=0        # titlebar height, in pixels

slop -o | tr 'x+' ' ' | {
    read w h x y
    w=$(( ( w - ( border / wglyph ) ) / wglyph ))
    h=$(( ( ( h - ( border / hglyph ) ) / hglyph ) - ( title / hglyph ) ))
    exec urxvt -uc -b 10 -geometry ${w}x${h}+${x}+${y} &
}

#P.S i have no idea about actual orgin of this script