var nav_delay    = 2000;
var nav_timer_id = null;
var nav_timer_on = false;


function nav_FlipOn(id) {

    if (id != nav_CurrentOn) {
        toGoOn  = document.getElementById('navSub' + id);
        toGoOff = document.getElementById('navSub' + nav_CurrentOn);

        toGoOff.style.display = 'none';
        toGoOn.style.display = 'block';

        nav_CurrentOn = id;
    }
}

function nav_Revert() {

    toGoOn  = document.getElementById('navSub' + nav_CurrentLoc);
    toGoOff = document.getElementById('navSub' + nav_CurrentOn);

    toGoOff.style.display = 'none';
    toGoOn.style.display = 'block';

    nav_CurrentOn = nav_CurrentLoc;
}

function nav_startTimer() {

    nav_timer_id = setTimeout('nav_Revert()', nav_delay);
    nav_timer_on = true;
}

function nav_stopTimer() {

    if (nav_timer_on) {
        clearTimeout(nav_timer_id);
        nav_timer_on = false;
    }
}