var popupWindow = null;

function popup(url,width,height,x,y) {
    var top, left;

    top  = (screen.height - height) / 2;
    if (x && (x > 0)) left = x;
                 else left = (screen.width  - width)  / 2;
    popupWindow = window.open(url,'popupwindow','toolbar=no,menubar=no,scrollbars=yes,resizable=no,width='+width+',height='+height+',top='+top+',left='+left+'');
    popupWindow.focus();
}

function popup_woscroll(url,width,height,x,y) {
    var top, left;

    top  = (screen.height - height) / 2;
    if (x && (x > 0)) left = x;
                 else left = (screen.width  - width)  / 2;
    popupWindow = window.open(url,'popupwindow','toolbar=no,menubar=no,scrollbars=no,resizable=no,width='+width+',height='+height+',top='+top+',left='+left+'');
    popupWindow.focus();
}