Try add the msdropdown only on visible elements; then when you show items attach the plugin again.

Code:

$(document).ready(function () {
    $(".colormenu:visible").msDropDown();

    var spotMax = 4;
    if ($('.spot').size() &gt;= spotMax) {
        $(obj).hide();
    }

    $("#add").click(function () {
        addSpot(this, spotMax);
    });
});

function addSpot(obj, sm) {
    var num = eval($('.spot').size()) + 1;
    var upload_area = $('#upload_area').html();

    $('#spots').append('&lt;div class="spot"&gt;' + upload_area + '&lt;/div&gt;').find(".remove").click(function () {
        $(this).parent().remove();
        $('#add').show();
    });

    if ($('.spot').size() &gt;= sm) {
        $(obj).hide();
    }

     $(".colormenu:visible").msDropDown();
}


Demo: http://jsfiddle.net/Lz3aW/

Jquery dropdown with image doesn't show
Take a passage like this:



Fill in the blank: Each of these boxes denote a ______

Is there a single general term for these that's better than note or chord? Or maybe there's a term for "anything that has a duration" that also encompasses rests? It seems like enough of a fundamental concept that it should have a name.
