function win_popup_NoBars(URL, w, h) {
		if ((w == 0) || (h == 0))
		{
			w = screen.width * 0.75;
			h = screen.height * 0.75;
		}
		var leftCorner = (screen.width) ? (screen.width - w)/2 : 0;
		var topCorner = (screen.height) ? (screen.height - h)/2 : 0;
		var win = window.open(URL,'_popup_win','width=' + w + ',height=' + h + ',top=' + topCorner + ',left=' + leftCorner + ',toolbar=0,location=0,directories=0,status=0,menubar=0,scrollbars=0,resizable=0');
		win.focus();
	} 

	function impressum() {
		win_popup_NoBars('http://www.vier-fuer-texas.de/impressum.html', 281, 401);
	}