function popup(url, name, width, height) {
    var scrollbars = "no";
    if(width > screen.width) {
        width = screen.width;
        scrollbars = "yes";
    }
    if(height > screen.height) {
        height = screen.height;
        scrollbars = "yes";
        width += 17;
    }

    var left = (screen.width-width)/2;
    var top = (screen.height-height)/2;
    if (left < 0) {
        left = 0;
    }
    if (top < 0) {
        top = 0;
    }

    var pars = "height=" + height + ",width=" + width + ",top=" + top + ",left=" + left + ",scrollbars=" + scrollbars +
        ",location=no,menubars=no,toolbars=no,resizable=no,status=yes";
    var w = window.open(url, name, pars);
    if(w) {
        w.focus();
    }
}