function showhide(dothis) {
        if (document.getElementById(dothis).style.display == 'block')
              document.getElementById(dothis).style.display = 'none';
        else
              document.getElementById(dothis).style.display = 'block';
     }

     function chgmenu(number) {
       if (oldnumber)
          document.getElementById('menu' + oldnumber).style.display == 'none'   
       document.getElementById('menu' + number).style.display = 'block';
       var oldnumber = number;
     }