function popup(page,nom,large,haut){
var xMax = screen.width;
var yMax = screen.height;
var xOffset = (xMax - large)/2;
var yOffset = (yMax - haut)/2;
window.open(page,nom,'width='+large+',height='+haut+',top='+yOffset+',left='+xOffset+',menubar=no,resizable=no,scrollbars=no,toolbar=no');
}