function pokaz_warstwe(id)
{ 
  eval("menu0_a.style.visibility='hidden'");
  eval("menu1_a.style.visibility='hidden'");
  eval("menu2_a.style.visibility='hidden'");
  eval("menu3_a.style.visibility='hidden'");
  eval("menu4_a.style.visibility='hidden'");
  eval("menu5_a.style.visibility='hidden'");
  eval("menu"+id+"_a.style.visibility='visible'");
}
function ukryj_warstwe()
{ 
  eval("menu0_a.style.visibility='hidden'");
  eval("menu1_a.style.visibility='hidden'");
  eval("menu2_a.style.visibility='hidden'");
  eval("menu3_a.style.visibility='hidden'");
  eval("menu4_a.style.visibility='hidden'");
  eval("menu5_a.style.visibility='hidden'");
}