Popup scorrevole

[star23]

ho inserito questo script
<SCRIPT>

<!--
var popwindow
var popwindowwidth=250
var popwindowheight=280
var popwindowtop=200
var popwindowURL="popup.html"
var waitingtime=3
var pause=100
var step=10
var popwindowleft=-popwindowwidth-50
var marginright
var pagecenter
var timer

waitingtime= waitingtime*2500

function showWindow() {
popwindow = window.open(popwindowURL, "popwindow", "toolbar=no,width="+popwindowwidth+",height="+popw indowheight+",top="+popwindowtop+",left="+(-popwindowwidth)+"");
if (document.all) {
marginright = screen.width+50
}
if (document.layers) {
marginright = screen.width+50
}
pagecenter=Math.floor(marginright/2)-Math.floor(popwindowwidth/2)
movewindow()
}

function movewindow() {
if (popwindowleft<=pagecenter) {
popwindow.moveTo(popwindowleft,popwindowtop)
popwindowleft+=step
timer= setTimeout("movewindow()",pause)
}
else {
clearTimeout(timer)
timer= setTimeout("movewindow2()",waitingtime)
}
}

function movewindow2() {
if (popwindowleft<=marginright) {
popwindow.moveTo(popwindowleft,popwindowtop)
popwindowleft+=step
timer= setTimeout("movewindow2()",pause)
}
else {
clearTimeout(timer)
popwindow.close()
}
}

// -->
</SCRIPT>

e funziona benissimo solo che ho un dubbio, è compatibile con netscape?

se no come possop fare?