function opnWindow(url) {
var width = 520
var height = 412
var leftPx = ( screen.availWidth - width ) / 2;
var topPx = ( screen.availHeight - height ) / 2;
var params = "width=" +width+ ", height=" +height+ ", resizable=yes, scrollbars=yes, top=" +topPx+ ", left=" +leftPx;
window.open(url, 'newWindow', params);
}