function popup(id) {
	var e = document.getElementsByTagName('div');
	for (i = 0; i < e.length; i++) {
		if (e[i].className == 'popup_'+id) {
			e = e[i];
			break;
		}
	}
	if (e.style.display == 'block') {
		e.style.display = 'none';
		e.parentNode.removeChild(document.getElementById('curtain'));
		return false;
	}
	var curtain = document.createElement('p');
	curtain.id = 'curtain';
	curtain.onclick = function() { return popup(id); };
	e.parentNode.insertBefore(curtain, e);
	e.style.display = 'block';
	if (window.innerWidth) {
		e.style.left = ((window.innerWidth - e.offsetWidth) / 2)+'px';
		e.style.top = ((window.innerHeight - e.offsetHeight) / 2)+'px';
	} else {
		e.style.left = ((document.documentElement.clientWidth - e.offsetWidth) / 2)+'px';
		e.style.top = ((document.documentElement.clientHeight - e.offsetHeight) / 2)+'px';
	}
}