function Show(id,area,useToggle) {
    // layer already visible, user tries to switch it on again
    if (current[area] == id && !useToggle) {
        // this makes the effect that the layer disapears again when
        // the users clicks a second time on the same link
        Hide(id,area);
    } else {
        // layer that the user wants to be displayed is not yet visible
        Hide(current[area],area);
        document.getElementById(id).style.display = "block";
        current[area] = id;
    }
}

function Hide(id,area) {
    if (id) {
        document.getElementById(id).style.display = "none";
        current[area] = '';
    }
}