function montrer_cacher(leCalk)
{
    //l'élément est caché, on l'affiche
    if (document.getElementById(leCalk).style.display == "none")
    {
        document.getElementById(leCalk).style.display = "block";
    }
    //l'élément est affiché, on le cache
    else
    {
        document.getElementById(leCalk).style.display = "none";
    }
}