function popup(url){
   	var w = (screen.availWidth) / 2 - 300;
	var h = (screen.availHeight) / 2 - 250;
    var li = window.open(url,"","width=640,height=405,left=" + w + ",top=" + h + ",resizable");
}

function popdown(url) {
	window.opener.location.href = url;
	parent.self.close();
}