function popup_centrata(popup_file, popup_width, popup_height, popup_target) {

    var xscreen;
    var yscreen;

    yscreen = Math.round((screen.availHeight - popup_height) / 2)
    xscreen = Math.round((screen.availWidth - popup_width) / 2)
    popup_target = (popup_target) ? popup_target : "Popup1"
    frmRub = open(popup_file, popup_target, "scrollbars=no,resizable=yes,width=" + popup_width + ",height=" + popup_height + ",screenX=" + xscreen + ",left=" + xscreen + ",top=" + yscreen + ",screenY=" + yscreen);
    return frmRub;
}