function menu_image_on(id,on_off) {
    $(id).setStyle({
	'background-image': 'url(/images/yellow_crayon_with_border.gif)'
	    });
}

function menu_image_off(id) {
    $(id).setStyle({
	'background-image': 'url(/images/red_crayon_with_border.gif)'
	    });
}