function popup(url, w, h) {
	var t = ((document.body.clientHeight/2)-(h/2));
	var l = ((document.body.clientWidth/2-(w/2)));
	
	window.open(url, '','left='+l+',top='+t+',width='+w+',height='+h+',location=no,scrollbars=no');
}

function height() {
	var body_h = document.body.clientHeight;
	var main_div = document.getElementById('main_div');
	if (main_div) {
		if (body_h > main_div.clientHeight) {
			main_div.style.height = body_h+'px';
		}
	}
}