Por si a alguien le interesa:
<html>
<head>
<script>
var windowW=screen.width// wide
var windowH=screen.height-30 // high
var windowX = 0 // from left
var windowY = 0 // from top
var urlPop = "pop.htm"
var title = "Titulo del Pop"
var autoclose = false
s = "width="+windowW+",height="+windowH;
var beIE = document.all?true:false
function openFrameless(){
if (beIE){
NFW = window.open("","popFrameless","fullscreen,"+s)
NFW.blur()
window.focus()
NFW.resizeTo(windowW,windowH)
NFW.moveTo(windowX,windowY)
var frameString=""+
"<html>"+
"<head>"+
"<title>"+title+"</title>"+
"</head>"+
"<frameset rows='*,0' framespacing=0 border=0 frameborder=0>"+
"<frame name='top' src='"+urlPop+"' scrolling=auto>"+
"<frame name='bottom' src='about
:blank' scrolling='no'>"+
"</frameset>"+
"</html>"
NFW.document.open();
NFW.document.write(frameString)
NFW.document.close()
} else {
NFW=window.open(urlPop,"popFrameless","scrollbars, "+s)
NFW.blur()
window.focus()
NFW.resizeTo(windowW,windowH)
NFW.moveTo(windowX,windowY)
}
NFW.focus()
if (autoclose){
window.onunload = function(){NFW.close()}
}
}
</script>
</head>
<body onload="openFrameless()">
<p>
</body>
</html>