var actlayer = '';
	     
function set_menue(layer) {
  document.getElementById(layer).style.visibility='visible'; 
  document.getElementById('lastlayer').style.visibility='visible'
  actlayer=layer;
}

function reset_layer() {
  document.getElementById(actlayer).style.visibility='hidden';
  document.getElementById('lastlayer').style.visibility='hidden';
  actlayer='';
}