function popupopen() {		// parameter.reihenfolge: URL, WIDTH, HEIGHT
	var w,h,url,aw,ah;
	var a=popupopen.arguments;
	if (a.length==0) return;
	url=a[0];
	if (a.length>1) {
		w=a[1]; h=a[2];
	}
	else {
		w=450; h=400
	}
	win=window.open(url,'win_front','toolbar=no,location=no,directories=no,status=yes,menubar=no,scrollbars=yes,resizable=no,copyhistory=no,width='+w+',height='+h);
	if (screen) {
		aw=screen.availWidth;
		ah=screen.availHeight;
		win.moveTo(((aw/2)-(w/2)),((ah/2)-(h/2)));
	}
	win.focus();
}