function showinfos(element){
        document.getElementById(element).style.visibility = 'visible';
}
function displayblock(element){
        document.getElementById(element).style.display = 'block';
}
function hideinfos(element){
        document.getElementById(element).style.visibility = 'hidden';
}
function displaynone(element){
        document.getElementById(element).style.display = 'none';
}