function toggleElm(id) {
    var isShowingNow = null;
    var elm = document.getElementById(id);
    if (elm) {
        if (elm.style.display == 'block') {
            elm.style.display = 'none';
            isShowingNow = false;
        }
        else {
            elm.style.display = 'block';
            isShowingNow = true;
        }
    }
}