function centerWindow() {
if (document.all)
var xMax = screen.width, yMax = screen.height;
else
if (document.layers)
var xMax = window.outerWidth, yMax = window.outerHeight;
else
var xMax = 420, yMax = 230;
var xOffset = (xMax -420)/2, yOffset = (yMax -600)/2;
window.open('informations_legales.html','windowbis','width=420,height=230,scrollbars=no,screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+'');
}