var popup;

function popup_open(url, left, top, width, height, scrollbars, resizable) {
        popup_close();
        popup = window.open(url, 'popup', 'left=' + left + ',top=' + top + ',width=' + width + ',height=' + height + ',scrollbars=' + scrollbars + ',resizable=' + resizable + ',channelmode=0,directories=0,fullscreen=0,location=0,menubar=0,status=0,toolbar=0');
}

function popup_close() {
    if (popup != null) {
        if (popup.closed != true) {
            popup.close();
        }
    }
}