pultroppo no, modificando delle funzioni di Dreamwever in maniera che
funzionasse anche con Netscape, ho provato a trovare il width, ma se
questo non è specificato nello style, non me lo trova 
Per capirci il mio esperimento è stato questo
codice:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>Documento senza titolo</title>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<script language="JavaScript" type="text/JavaScript">
<!--
function MM_reloadPage(init) { //reloads the window if Nav4 resized
if (init==true) with (navigator) {if ((appName=="Netscape")&&(parseInt(appVersion)==4)) {
document.MM_pgW=innerWidth; document.MM_pgH=innerHeight; onresize=MM_reloadPage; }}
else if (innerWidth!=document.MM_pgW || innerHeight!=document.MM_pgH) location.reload();
}
MM_reloadPage(true);
function MM_findObj(n, d) { //v4.01
var p,i,x; if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
if(!x && d.getElementById) x=d.getElementById(n); return x;
}
function MM_showHideLayers() { //v6.0
var i,p,v,obj,args=MM_showHideLayers.arguments;
for (i=0; i<(args.length-2); i+=3) if ((obj=MM_findObj(args[i]))!=null) { v=args[i+2];
if (obj.style) { obj=obj.style; v=(v=='show')?'visible':(v=='hide')?'hidden':v; }
//obj.visibility=v;
document.write('larghezza ' + obj.width);}
}
//-->
</script>
</head>
<body>
<div id="menu" style="position:absolute; left:18px; top:23px; height:140px; z-index:1; background-color: #FF0000; layer-background-color: #FF0000; border: 1px none #000000; visibility: visible;">ciao</div>
<div id="pulsante" style="position:absolute; left:187px; top:28px; height:56px; z-index:2; background-color: #999966; layer-background-color: #999966; border: 1px none #000000; visibility: visible;" onClick="MM_showHideLayers('menu','','hide')">ola</div>
<div id="Layer1" style="position:absolute; left:256px; top:24px; height:26px; z-index:3; background-color: #99FF99; layer-background-color: #99FF99; border: 1px none #000000;" onClick="MM_showHideLayers('menu','','show')">mostra</div>
</body>
</html>
Altre idee?