function pop(title, width, height, filename)
{
	thefile=filename;
	var w = 480, h = 340;

	if (document.all || document.layers) {
	w = screen.availWidth;
	h = screen.availHeight;
	}

	var leftPos = (w-width)/2, topPos = (h-height)/2;
	
	popbox=window.open(thefile,title,"toolbar=no,scrollbars=no,resizable=yes,directories=no,menubar=no,width="+width+",height="+height+",top=" + topPos + ",left=" + leftPos);
	if(popbox !=null)
	{
		if (popbox.opener==null)
		{
			popbox.opener=self;
		}
	}
}