// a function to reveal a layer
function show_apple()
{
  // reference the layer by id
  var obj = document.getElementById("lyr");
  // show the layer                    
  obj.style.visibility= "visible";        
}

// a function to hide a layer
function hide_apple()
{
  // reference the layer by id
  var obj = document.getElementById("lyr");
  // hide the layer                    
  obj.style.visibility= "hidden";        
}