function centerWindow(address, height) {
	var xMax = screen.width;
	var yMax = screen.height;
    var locationX = ((xMax - 800)/2) - 10;

if ( height === undefined) {
  h = 600;
} else {
  h = height;
}
	var locationY = (yMax - h)/2;
    window.open(address,'','width=800,resizable=no,height=' + h + ',scrollbars=yes,left=' + locationX + ',top=' + locationY);
}