var popup = '' ;

function openWindow(url, n, w, h, xpos, ypos) {
	if (!popup.closed && popup.location) {
	popup.focus();
	}
	else {
	xpos = (screen.width-w)/2;
	ypos = (screen.height-h)/2;
	var windowprops = "scrollbars='no',width=" + w + ",height=" + h +",left=" + xpos +",top="+ ypos;
	var windowname = n;
	
	popup = window.open(url,windowname,windowprops,true);
		if(window.focus){
		popup.focus();
		}
	}
}