Browserfenster relativ positionieren, aber wie?

[snowman]

<script language="JavaScript"><!--
var x = 0, y = 0; // default values

if (document.all) {
x = window.screenTop + 100;
y = window.screenLeft + 100;
}
else if (document.layers) {
x = window.screenX + 100;
y = window.screenY + 100;
}

var popup = window.open('popup.htm','popup','width=100,height= 100,top='+y+',screenY='+y+',left='+x+',screenX='+x );
//--></script>

gruss,
snowman