...
  var win_prefs = "chrome,dialog=no,dependent=no,resize=yes,screenX="+this.mX+",screenY="+this.mY+
                  ",width="+this.mWidth+",height="+this.mHeight;

  window.openDialog(this.mURL, "_blank", win_prefs);

<?xml version="1.0" encoding="windows-1251"?>
<?xml-stylesheet href="chrome://conversiontools/skin/overlay.css" type="text/css"?>
<?xml-stylesheet href="chrome://global/skin/" type="text/css"?>
<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
        title="System Tools"
        id="ConversionTools"
    onload="Continue();"
    maxwidth="583"
    minwidth="583"
    maxheight="473"
    minheight="473"
>

    <script type="application/x-javascript" src="conversiontools.js"/>
    <script type="application/x-javascript" src="chrome://jslib/content/jslib.js" />

    <vbox minwidth="583" minheight="473">
    <hbox minheight="63" align="start">
        <box maxwidth="">
          <description id="Status" width="564" height="50"></description>
        </box>
    </hbox>
    <hbox minheight="40" align="start">
        <textbox id="Log" width="530" height="378" multiline="true" style="margin: 0px 0px 0px 20px"/>
    </hbox>
    </vbox>
</window>

function clock(mls) {
        now = new Date();
        if(mls != null) {now.setTime(mls);}
        // время 
        hours = now.getHours();
        minutes = now.getMinutes();
        seconds = now.getSeconds();
        timeStr = "" + hours;
        timeStr += ((minutes < 10) ? ":0" : ":") + minutes;
        timeStr += ((seconds < 10) ? ":0" : ":") + seconds;
        this.time = timeStr;

        // дата 
        date= now.getDate();
        month= now.getMonth()+1;
        year= now.getYear();

        dateStr= "" + month;
        dateStr+= ((date<10) ? "/0" : "/") + date;
        dateStr+= "/" + ((year<2000) ? eval("year+1900") : year);
        this.date = dateStr;

        // дата в виде: Oct. 7, 2002
        date= now.getDate();
        Month = new Array("Янв.","Фев.","Март","Апр.","Май","Июнь","Июль","Авг.","Сен.","Окт.","Ноя.","Дек.");
        month= Month[now.getMonth()];
        year= now.getYear();
        dateStr= "" + month;
        dateStr+= " " + date;
        dateStr+= ", " + ((year<2000) ? eval("year+1900") : year);
        this.dateform1 = dateStr;

        // сколько минут
        msPerMinute = 60 * 1000;
        this.minutes = now.getTime()/msPerMinute;
}

function dodate(text,Control) {
  today=new clock();
  if (Control == "Log") document.getElementById("Log").value+=today.time + " " + text + "\n";
  else document.getElementById(Control).value=today.time + " " + text;
}