#!/bin/bash

single() {
    xrandr \
	--output LVDS --mode 1280x800 --pos 0x0 --dpi 96 \
	--output VGA --off
}

dual() {
    xrandr \
	--output VGA --mode 1280x1024 --pos 0x0 --dpi 96 \
        --output LVDS --mode 1280x800 --pos 0x1024 --dpi 96
}

twm &

dual
sleep 3
glxgears # works anywhere on the screen
single
sleep 3
chvt 1
sleep 3
chvt 10 # x vt
sleep 3
dual
glxgears # works only in the topleft 1280x800 corner
xterm