function show(ww,wh,site) {
	
		var w = ww; 
		var h = wh; //soll ja quadratisch und deshalb fensterkopf abziehen. ist in allen BS in etwa 20px;
		
        x = (screen.availWidth-w)/2;
        y = (screen.availHeight-h)/2;
        var popupWindow = window.open(site,'Isbb','width='+w+',height='+h+',left='+x+',top='+y+',resizable,scrollbars,location=no');
}