var myWindow;
function openCenteredWindow(url,width,height,scrollbars) {
//var width = 420;
//var height = 450;
var left = parseInt((screen.availWidth/2) - (width/2));
var top = parseInt((screen.availHeight/2)- (height/2));
var windowFeatures = "width=" + width + ",height=" + height +
",status,resizable,left=" + left + ",top=" + top + ",scrollbars=" + scrollbars +
",screenX=" + left + ",screenY=" + top;
myWindow = window.open(url, "_blank", windowFeatures);
}