function opensubmenu(submenu)
{
  document.getElementById(submenu).style.display='block';
}

function closesubmenu(submenu)
{
  document.getElementById(submenu).style.display='none';
}

function togglesubmenu(submenu)
{
  if(document.getElementById(submenu).style.display=='block')
  {
    document.getElementById(submenu).style.display='none';
  }
  else{
    /* Closing all other elements, specific for only this site */
    document.getElementById('submenu_bedrijven').style.display='none';
    document.getElementById('submenu_opleidingen').style.display='none';
    /* ------------------------------------------------------- */
    
    document.getElementById(submenu).style.display='block';
  }
}