var prevShown;

        function show(id) {
                if (document.getElementById(id).className.indexOf('show') > -1) {
                        isVisible = 1;
                        document.getElementById(id).className = '';
                        if (prevShown && prevShown != id && document.getElementById(prevShown).className.indexOf('show') <= -1) {
                                document.getElementById(prevShown).className = 'show';
                        }
                } else {
                        isVisible = 0;
                        document.getElementById(id).className = 'show';
                }
                prevShown = id;
        }