//popup toujours centree
function popup(ul,lx,ly) {
if (document.all){
var xMax = screen.width, yMax = screen.height;}
else
if (document.layers)
var xMax = window.outerWidth, yMax = window.outerHeight;
else 
var xMax = 800, yMax=600;
var xOffset = (xMax - lx)/2, yOffset = (yMax - ly)/2-40;
fen = open(ul,'fen','scrollbars=0,toolbar=0,menubar=0,resizable=1,width='+lx+',height='+ly+',screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+'');
}