function openCenteredPopUpWin(url, width, height, fixed) {

    var left = (screen.width-width)/2;
    var top = (screen.height-(height+32))/2;

    var optStr =
        "width="+width+",height="+height+","+'left='+left+',top='+top+","+
        "toolbar=no,menubar=no,statusbar=no,"+
        (fixed ?
            "resizable=no,scrollbars=no" : "resizable=yes,scrollbars=yes"
        )
    ;

    var win = open(url, "_blank", optStr);
    win.focus();
}