function abre_topico(nume)
   {
      if(document.getElementById("num"+nume).style.visibility=="hidden")
	  {
	     document.getElementById("num"+nume).style.display="block";
	     document.getElementById("num"+nume).style.position="relative";
	     document.getElementById("num"+nume).style.visibility="visible";
	  }else
	  {
	     document.getElementById("num"+nume).style.display="none";
	     document.getElementById("num"+nume).style.position="absolute";
	     document.getElementById("num"+nume).style.visibility="hidden";
	  }
   }
   
   function muda_imagem_mestre(novo_src)
   {
      document.getElementById("imagem_mestre").src=novo_src;
   }