var num_menus = 1;

function show(id)
{
  var menuelement;
 
  //Hide all menus
  for (i=1;i<=num_menus;i++)
  {
    menuelement=document.getElementById('submenu'+i);
    menuelement.style.display = 'none';
  }
  
  menuelement=document.getElementById(id);
  
  if (menuelement)
  {
    //Show selected menu
    menuelement.style.display = 'block';
  }
  
  return;
}