var t;
    var feature = '#feature_';
    var control = '#cntrl_';


    // initialize variables at last position
    var current = 4;
    var next = 1;
    var previous = 3;
    $('#cntrl_play').hide();
    function start_loop() {
        $('#cntrl_play').hide();
        $(control.concat(current)).removeClass("cntrl_active");
        hide_element(feature.concat(current));
        current = next;
        $(control.concat(next)).addClass("cntrl_active");
        if (current == 4) {
            next = 1;
        } else {
            next = current + 1;
        }
        if (current == 1) {
            previous = 4;
        } else {
            previous = current - 1;

        }
        show_element(feature.concat(current));
        t = setTimeout("start_loop()",8000);

    }

    function restart_loop() {
        // this is required to avoid odd behavior if Play is clicked when not paused
        $('#cntrl_pause').show();
        $('#cntrl_play').hide();
        clearTimeout(t);
        $(control.concat(current)).removeClass("cntrl_active");
        hide_element(feature.concat(current));
        if (current == 4) {
            next = 1;
        } else {
            next = current + 1;
        }
        if (current == 1) {
            previous = 4;
        } else {
            previous = current - 1;
        }

        current = next;
        $(control.concat(current)).addClass("cntrl_active");
        show_element(feature.concat(current));
        t = setTimeout("restart_loop()",8000);

    }

    function show_element(div) {
        $(div).fadeIn(2000);
		//$(div).show();
    }

    function hide_element(div) {
        //$(div).fadeOut("slow");
		$(div).hide();
    }

    function stop_loop() {
        $('#cntrl_pause').hide();
        $('#cntrl_play').show();
        clearTimeout(t);

    }

    function switch_pane(div) {
        stop_loop();
        $("#cntrl_1").removeClass("cntrl_active");
        $("#feature_1").hide();
        $("#cntrl_2").removeClass("cntrl_active");
        $("#feature_2").hide();
        $("#cntrl_3").removeClass("cntrl_active");
        $("#feature_3").hide();
        $("#cntrl_4").removeClass("cntrl_active");
        $("#feature_4").hide();

        current = div - 1;

        $(control.concat(div)).addClass("cntrl_active");
        show_element(feature.concat(div));

    }

    $(document).ready(function() {
        start_loop();

    });