function $(e){
	return document.getElementById(e);
}

function toggle_visible(e, show){
	o = $(e);
	if (show)
		o.style.display = 'block';
	else
		o.style.display = 'none';
}

function flip_img(e){
	img = e.firstChild;
	old = img.src;
	img.src = e.rel;
	e.rel = old;
}