var menu1 = false;
    var menu2 = false;
  
    function showSubmenu(id)
    {
      if ( document.getElementById("submenu"+id).style.display == 'none' )
        document.getElementById("submenu"+id).style.display = 'block';
    }
    function hideSubmenu(id)
    {
      if ( document.getElementById("submenu"+id).style.display == 'block' )
        document.getElementById("submenu"+id).style.display = 'none';
    }
    
    function setVisibility(id)
    {
      eval('m = menu'+id+';');
      
      if ( !m )
      {
        eval('menu'+id+' = true;');
        document.getElementById("submenu"+id).style.display = 'block';
      }
    }
    
    function setInvisibility(id)
    {
      eval('m = menu'+id+';');
      
      if ( m )
      {
        eval('menu'+id+' = false;');
        document.getElementById("submenu"+id).style.display = 'none';
      }
    }