/**
	 * Opens a popup at the given url. width, height and name are optional.
	 */
	function popup(url, width, height, name)
	{
		window.focus() ; // so not to leave focus on link
		if(window.open){
			try {
	
				if(!url)		var url		= 'about:blank' ;
				if(!width)	var width	= 516 ;
				if(!height)	var height	= 420 ;
				if(!name)	var name	= 'popup' ;
				
				var left		= (screen.width - width)/2 ;
				var top		= (screen.height - height - 100)/2 ;
				var tools	= 'width=' + width + ',height=' + height + ',left=' + left + ',top=' + top + ',resizable=yes,scrollbars=yes,toolbar=no,location=no' ;
				var popup	= window.open(url, name, tools) ;
				
				popup.focus() ;
				return popup ;

			} catch(e){}
		}
		alert('To use this feature, please instruct your web browser to allow popups from this website.') ;
		return false ;
	}