function helpmenu(width,height,url,center) {
	if (center) {
		var left=(screen.width-width-10)/2;
		var top=(screen.height-height-20)/2;
	} else {
		var left=20;
		var top=20;
	}

	if (left<0) left=0;
	if (top<0) top=0;	

	var options = "toolbar=no,location=no,directories=no,status=no,menubar=no,scrollbars=no,resizable=yes,copyhistory=no,width="+width+",height="+height+",left="+left+",top="+top;
	var mypopup = window.open( url ,"popupwindow1", options);
	mypopup.moveTo(left, top);
}