function visibilite(blocID)
{
var targetElement;
targetElement = document.getElementById(blocID) ;
if (targetElement.style.display == "none")
{
targetElement.style.display = "" ;
} else {
targetElement.style.display = "none" ;
}
}
function invisibilite(blocID)
{
document.getElementById(blocID).style.display = 'none';
}