function showHideChildren(id) {
    if (document.getElementById('page'+id).className.toString().indexOf('invisible') == -1){
        document.getElementById('page'+id).className += 'invisible';
        document.getElementById('plusLink'+id).innerHTML = '+';
    } else {
        document.getElementById('page'+id).className = document.getElementById('page'+id).className.replace('invisible', '');
        document.getElementById('plusLink' + id).innerHTML = '–';
    }
}

function hideAll() {
    for (var i = 0; i < document.getElementById('rootList').getElementsByTagName('ul').length; i++) {
        document.getElementById('rootList').getElementsByTagName('ul')[i].className += ' invisible';
    }
}