var visible_layer = 'no';

function showLayer(layerid) {
    layer = document.getElementById(layerid);
    layer.style.visibility = "visible";
}

function hideLayer(layerid) {
    layer = document.getElementById(layerid);
    layer.style.visibility = "hidden";
}

function switcher(layerid) {
    layer = document.getElementById(layerid);
    if (layer.style.visibility == "hidden")
    {
    showLayer(layerid);
    visible_layer = layerid;
    }
    else
    {
    hideLayer(layerid);
    visible_layer = 'no';
    }
}

function Choice(layerid) {
    if (visible_layer == 'no' || visible_layer == layerid)
    {
    switcher(layerid);
    }
    else
    {
    hideLayer(visible_layer);
    switcher(layerid);
    }
}

function vanish() {
    if (visible_layer !== 'no')
    {
    hideLayer(visible_layer);
    }
}

function vanish2() {
    if (on == "no" && visible_layer !== 'no')
    {
    hideLayer(visible_layer);
    }
}

function vanish3() {
    if (turn == "on" && visible_layer !== 'no')
    {
    hideLayer(visible_layer);
    }
}