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 = 100, yMax=100;
var xOffset = (xMax - 100)/2, yOffset = (yMax -100)/2;
window.open('#.html','windowbis','width=100,height=100,screenX='+xOffset+',screenY='+yOffset+',top='+yOffset+',left='+xOffset+'');
}