Il codice è allegato in fondo nei tag CODE, è del menu in questione.
In pratica nel mio forum SMF nel tema che uso ho messo questo codice che mi funzionava benissimo, solo che con FF non va, o meglio funziona male perchè i menu si aprono ma si richiudono, funzionano bene solo se con il cursore vado sopra alla barra di navigazione del forum, se scendo velocemente sotto nel forum il menu rimane sempre aperto.

Ho creato un account limitato per la persone che volesse aiutarmi che ringrazio anticipatamente (tutto minuscolo):
www.darkforge.it
user: java
passw: java


I menu in questione sono quelli che scendono a tendina da Ricerca e Quick links.

Grazie

codice:
//Drop Down Tab Menu- Author: Dynamic Drive (http://www.dynamicdrive.com)
//Created/ updated: October 23rd, 06'


var tabdropdown={
disappeardelay: 250, //set delay in miliseconds before menu disappears onmouseout
disablemenuclick: true, //when user clicks on a menu item with a drop down menu, disable menu item's link?
downsymbol:'' , //HTML "symbol" to use to indicate this is a dropdown menu item. Enter ('') to disable.

//No need to edit beyond here////////////////////////
dropmenuobj: null, ie: document.all, firefox: document.getElementById&&!document.all, previousmenuitem:null,

getposOffset:function(what, offsettype){
var totaloffset=(offsettype=="left")? what.offsetLeft : what.offsetTop;
var parentEl=what.offsetParent;
while (parentEl!=null){
totaloffset=(offsettype=="left")? totaloffset+parentEl.offsetLeft : totaloffset+parentEl.offsetTop;
parentEl=parentEl.offsetParent;
}
return totaloffset;
},

showhide:function(obj, e, obj2){ //obj refers to drop down menu, obj2 refers to tab menu item mouse is currently over
if (this.ie || this.firefox)
this.dropmenuobj.style.left=this.dropmenuobj.style.top="-500px"
if (e.type=="click" && obj.visibility==hidden || e.type=="mouseover"){
if (obj2.parentNode.className.indexOf("default")==-1) //if tab isn't a default selected one
obj2.parentNode.className="selected"
obj.visibility="visible"
}
else if (e.type=="click")
obj.visibility="hidden"
},

iecompattest:function(){
return (document.compatMode && document.compatMode!="BackCompat")? document.documentElement : document.body
},

clearbrowseredge:function(obj, whichedge){
var edgeoffset=0
if (whichedge=="rightedge"){
var windowedge=this.ie && !window.opera? this.iecompattest().scrollLeft+this.iecompattest().clientWidth-15 : window.pageXOffset+window.innerWidth-15
this.dropmenuobj.contentmeasure=this.dropmenuobj.offsetWidth
if (windowedge-this.dropmenuobj.x < this.dropmenuobj.contentmeasure)  //move menu to the left?
edgeoffset=this.dropmenuobj.contentmeasure-obj.offsetWidth
}
else{
var topedge=this.ie && !window.opera? this.iecompattest().scrollTop : window.pageYOffset
var windowedge=this.ie && !window.opera? this.iecompattest().scrollTop+this.iecompattest().clientHeight-15 : window.pageYOffset+window.innerHeight-18
this.dropmenuobj.contentmeasure=this.dropmenuobj.offsetHeight
if (windowedge-this.dropmenuobj.y < this.dropmenuobj.contentmeasure){ //move up?
edgeoffset=this.dropmenuobj.contentmeasure+obj.offsetHeight
if ((this.dropmenuobj.y-topedge)<this.dropmenuobj.contentmeasure) //up no good either?
edgeoffset=this.dropmenuobj.y+obj.offsetHeight-topedge
}
this.dropmenuobj.style.borderTopWidth=(edgeoffset==0)? 0 : "1px" //Add 1px top border to menu if dropping up
}
return edgeoffset
},

dropit:function(obj, e, dropmenuID){
if (this.dropmenuobj!=null){ //hide previous menu
this.dropmenuobj.style.visibility="hidden" //hide menu
if (this.previousmenuitem!=null && this.previousmenuitem!=obj){
if (this.previousmenuitem.parentNode.className.indexOf("default")==-1) //If the tab isn't a default selected one
this.previousmenuitem.parentNode.className=""
tabdropdown.togglehiddenobj(this.previousmenuitem, 'visible')
}
}
this.clearhidemenu()
if (this.ie||this.firefox){
obj.onmouseout=function(){tabdropdown.delayhidemenu(obj)}
obj.onclick=function(){return !tabdropdown.disablemenuclick} //disable main menu item link onclick?
this.dropmenuobj=document.getElementById(dropmenuID)
this.dropmenuobj.onmouseover=function(){tabdropdown.clearhidemenu()}
this.dropmenuobj.onmouseout=function(){tabdropdown.dynamichide(e, obj)}
this.dropmenuobj.onclick=function(){tabdropdown.delayhidemenu(obj)}
this.showhide(this.dropmenuobj.style, e, obj)
this.dropmenuobj.x=this.getposOffset(obj, "left")
this.dropmenuobj.y=this.getposOffset(obj, "top")
this.dropmenuobj.style.left=this.dropmenuobj.x-this.clearbrowseredge(obj, "rightedge")+"px"
this.dropmenuobj.style.top=this.dropmenuobj.y-this.clearbrowseredge(obj, "bottomedge")+obj.offsetHeight+"px"
this.previousmenuitem=obj //remember main menu item mouse moved out from (and into current menu item)
tabdropdown.togglehiddenobj(obj, "hidden") //Hide (form) object drop down menu overlaps, if any
}
},

togglehiddenobj:function(obj2, visible){
var revvalue=obj2.getAttribute("rev")
if (typeof revvalue=="string" && revvalue.length>0 && document.getElementById(revvalue)!=null)
document.getElementById(revvalue).style.visibility=visible
},

contains_firefox:function(a, b) {
while (b.parentNode)
if ((b = b.parentNode) == a)
return true;
return false;
},

dynamichide:function(e, obj2){ //obj2 refers to tab menu item mouse is currently over
var evtobj=window.event? window.event : e
if (this.ie&&!this.dropmenuobj.contains(evtobj.toElement))
this.delayhidemenu(obj2)
else if (this.firefox&&e.currentTarget!= evtobj.relatedTarget&& !this.contains_firefox(evtobj.currentTarget, evtobj.relatedTarget))
this.delayhidemenu(obj2)
},

delayhidemenu:function(obj2){
this.delayhide=setTimeout(function(){tabdropdown.dropmenuobj.style.visibility='hidden'; if (obj2.parentNode.className.indexOf('default')==-1) obj2.parentNode.className=''; tabdropdown.togglehiddenobj(obj2, 'visible')},this.disappeardelay) //hide menu
},

clearhidemenu:function(){
if (this.delayhide!="undefined")
clearTimeout(this.delayhide)
},

initializetabmenu:function(menuid, opt_selectedmenuitem){
var menuitems=document.getElementById(menuid).getElementsByTagName("a")
for (var i=0; i<menuitems.length; i++){
if (parseInt(opt_selectedmenuitem)==i)
menuitems[i].parentNode.className+=" selected default"
if (menuitems[i].getAttribute("rel")){
var relvalue=menuitems[i].getAttribute("rel")
menuitems[i].onmouseover=function(e){
var event=typeof e!="undefined"? e : window.event
tabdropdown.dropit(this, event, this.getAttribute("rel"))
}
if (tabdropdown.downsymbol!="")
menuitems[i].innerHTML+=tabdropdown.downsymbol //Add symbol HTML to menu item's.
}
}
}

}