// popup windows
	var popwin = null;
	function popup(popupURL, popupWidth, popupHeight, scrolling, bars, menues, sizing) {
			popupTop = (screen.height) ? (screen.height-popupHeight)/2 : 0;
			popupLeft = (screen.width) ? (screen.width-popupWidth)/2 : 0;
			var args = 'toolbar=' +bars+ ',location=no,directories=no,status=no,menubar=' +menues+ ',scrollbars=' +scrolling+ ',resize=' +sizing+ ',width='+popupWidth+',height='+popupHeight+',left='+popupLeft+',top='+popupTop;
			if(popwin && !popwin.closed) popwin.close();
			popwin = window.open(popupURL, '', args);
	}