function toggleLevel(id) {
    var level = document.getElementById('c'+id);
    var img = document.getElementById('i'+id);
    if(level.style.display == 'block') {
        hideLevel(level, img);
    } else {
	showLevel(level, img);
    }
}

function hideLevel(id) {
    var level = document.getElementById('c'+id);
    var img = document.getElementById('i'+id);
    hideLevel(level, img);
}

function hideLevel(level, img) {
    level.style.display = "none";
    img.src = '/img/plus.gif';
    img.title = 'open';
}

function hideAll() {
    for(var i=0; ; i++) {
        var level = document.getElementById('c'+i);
        var img = document.getElementById('i'+i);
        if(level == null && img == null) break;
        if(level != null) {
            level.style.display = "none";
        }
        if(img != null) {
            img.src = '/img/plus.gif';
            img.title = 'open';
        }
    }
}

function showLevel(id) {
    var level = document.getElementById('c'+id);
    var img = document.getElementById('i'+id);
    showLevel(level, img);
}

function showLevel(level, img) {
    level.style.display = 'block';
    img.src = '/img/minus.gif';
    img.title = 'close';
}

function showAll() {
    for(var i=0; ; i++) {
        var level = document.getElementById('c'+i);
        var img = document.getElementById('i'+i);
        if(level == null && img == null) break;
        if(level != null) {
            level.style.display = "block";
        }
        if(img != null) {
            img.src = '/img/minus.gif';
            img.title = 'close';
        }
    }
}