var overlay_form_id = 'overlay_div';
    var overlay_timeout_sek =  20;
    var overlay_timeout = null;
    var overlay_active  = true;
    var overlay_cookie  = null;
    var overlay_div     = null;

    function show_overlay(){
        if (true == overlay_active) {
            overlay_div = get_overlay_form();
            overlay_div.style.display    = 'block';
            overlay_div.style.left       = '40%';       
            overlay_div.style.top        = '200px';      
        }
    }
    
    function get_overlay_form() {
        return document.getElementById(overlay_form_id);
    }
    
    function overlay_timer_start() { 
        if (true == overlay_active) {
            window.clearTimeout(overlay_timeout);
            overlay_timeout = window.setTimeout('show_overlay()', overlay_timeout_sek * 1000)
        }
    }
    
    function overlay_timer_stop() { 
        if (true == overlay_active) {
            window.clearTimeout(overlay_timeout);
        }
    }
    
    function init_overlay() {
        overlay_cookie = cookieManager.getCookie('overlay_active');
        
        if (overlay_cookie) {
            if (overlay_cookie == 'inactive') {
                overlay_active = false;
            }
        }
        overlay_timer_start();
    }
    
    function set_overlay_inactive() {
        var jetzt = new Date();
        var Auszeit = new Date((jetzt.getTime() + 86400));        
        hide_overlay();
        document.cookie = escape('overlay_active') + '=' + escape('inactive') + (Auszeit ? '; expires=' + Auszeit.toGMTString() : '');
    }
    
    function hide_overlay() {
        overlay_div = get_overlay_form();
        overlay_div.style.display    = 'none';
        overlay_timer_stop();
    }
    
    window_onload_register(function() {
    init_overlay();
    })