function activate_link(current_link) {
    current_link.style.color="navy";
    current_link.style.textDecoration = "underline";
}

function deactivate_link(current_link) {
    current_link.style.color="maroon";
    current_link.style.textDecoration = "none";
}
function activate_map(current_map) {
    id = current_map.id;
    layer = document.getElementById("layer"+id);
    layer.style.visibility = "visible";
}
function deactivate_map(current_map) {
    id = current_map.id;
    layer = document.getElementById("layer"+id);
    layer.style.visibility = "hidden";
}


