var timerID;

function ShowLayer(id)
{
  document.getElementById().style.display = "block"; 
}

function HideTimedLayer(id)
{  
    clearTimeout(timerID);
    document.getElementById(id).style.display = "none";
}

function timedLayer(id)
{
  setTimeout("HideTimedLayer(\"" + id + "\")", 20000);
}