function MostrarCategoria(obj, superior)
{
  if (document.getElementById) {
    el=document.getElementById(obj);
    el_img=document.getElementById(obj.replace("cat","img"));
    ar=document.getElementById(superior).getElementsByTagName("div"); 

    if (el.style.display != "block") { 
      for (var i=0; i<ar.length; i++) {
        if (ar[i].id!=el.id && ar[i].className!="menuprincipal" && ar[i].className!="menuprincipal2") {
          ar_img=document.getElementById(ar[i].id.replace("cat","img"));
          if (ar_img && ar_img.src.substr(ar_img.src.length-10)=="cerrar.gif") {
            ar_img.src="/img/tr/simbolo_abrir.gif";
          }
          ar[i].style.display="none"; }}
      el.style.display = "block";
      if (el_img)
        el_img.src = "/img/tr/simbolo_cerrar.gif"; }
    else {
      if (el.className!="menuprincipal") {
        el.style.display = "none";
        if (el_img)
          el_img.src = "/img/tr/simbolo_abrir.gif"; }}}
}