function openPopup(file) {
    var top = 200;
    var left = (screen.width / 2) - 175;
    var height = 270;
    var width = 350;
    parameterstring = "height=" + height + ",width=" + width + ",menubar=no,scrollbars=yes,status=no,location=no,top=" + top + ",left=" + left;
    window.open(file,'Window',parameterstring);
}