function displayToggle(id) { 
  var el = document.getElementById(id).style; 
  if(el.display == "none") { 
    el.display = "block";
    eval("document.i"+id+".src='/images/icon_minus.gif'");
  }
  else if(el.display == "block") { 
    el.display = "none";
    eval("document.i"+id+".src='/images/icon_plus.gif'");
  } 
}