请大家帮小弟我看看这段树型菜单的代码，如果要增加下级菜单的话如何写？

请大家帮我看看这段树型菜单的代码，如果要增加下级菜单的话怎么写？急急！！！
请大家帮我看看这段树型菜单的代码，如果要增加下级菜单的话怎么写？急急！！！

文件名：menu.js

var   mimgpath= "images/ ";
var   mfonts= "style=\ "text-decoration:none;font-family:   宋体;   font-size:   9pt;   color:   #000000;   \ " ";
var   movercolor= "#0000FF ";
var   mnormalcolor= "#000000 ";
var   NC6=(navigator.userAgent.indexOf( "Netscape6 ")> 0)?true:false;
var   IE=(document.all)?true:false;
function   mOver(id)   {
if   (IE)   {eval(id).style.color=movercolor;   }  
else   if(NC6){   document.getElementById(id).style.color=movercolor;}
}
function   mOut(id)   {
if   (IE)   {eval(id).style.color=mnormalcolor;   }  
else   if(NC6){   document.getElementById(id).style.color=mnormalcolor;}
}

function   mFolderExpand($1,$2,pic)   {
if   (IE)   {   mExpandIE($1,$2,pic)   }  
else   if(NC6){   mExpandNC($1,$2,pic)   }
}

function   mExpandIE($1,$2,pic)   {
Expanda   =   eval($1   +   "a ");
Expanda.blur()
ExpandChild   =   eval($1   +   "Child ");
        if   ($2   !=   "top ")   {  
ExpandTree   =   eval($1   +   "Tree ");
ExpandFolder   =   eval($1   +   "Folder ");
}
if   (ExpandChild.style.display   ==   "none ")   {
ExpandChild.style.display   =   "block ";
                if   ($2   !=   "top ")   {  
                        if   ($2   ==   "last ")   {   ExpandTree.src   =   mimgpath+ "/Lminus.gif ";   }
else   {   ExpandTree.src   =   mimgpath+ "/Tminus.gif ";   }
ExpandFolder.src   =   mimgpath+ "/openfolder "+pic+ ".gif ";
}
else   {   mmTree.src   =   mimgpath+ "/topopen1.gif ";   }
}else{
ExpandChild.style.display   =   "none ";
                if   ($2   !=   "top ")   {  
                if   ($2   ==   "last ")   {   ExpandTree.src   =   mimgpath+ "/Lplus.gif ";   }
else   {   ExpandTree.src   =   mimgpath+ "/Tplus.gif ";   }
ExpandFolder.src   =   mimgpath+ "/folder "+pic+ ".gif ";
}
else   {   mmTree.src   =   mimgpath+ "/top1.gif ";   }
}
}
function   mExpandNC($1,$2,pic)   {
Expanda   =   document.getElementById($1   +   "a ");
Expanda.blur()
ExpandChild   =   document.getElementById($1   +   "Child ");
        if   ($2   !=   "top ")   {  
ExpandTree   =   document.getElementById($1   +   "Tree ");
ExpandFolder   =   document.getElementById($1   +   "Folder ");
}
if   (ExpandChild.style.display   ==   "none ")   {
ExpandChild.style.display   =   "block ";