jQuery Forum

$('.draggable').draggable({
iframeFix: true,
helper: 'clone',
revert: 'invalid',
drag: function (event, ui) {
    externalIframeContents.find('.getting-hovered-by-helper').css('box-shadow', '');
    externalIframeContents.find('.ui-droppable').droppable("destroy");
    var m_ui = ui;
    clearTimeout(timer);
    timer = setTimeout(function () {
        // if dragging is stopped for 500 seconds do this
        if(m_ui.position.top > iframeTop) {
            var elementBehindTheHelper = externalIframeDocument.elementFromPoint(m_ui.position.left + m_ui.helper.width() / 2, (m_ui.position.top - iframeTop) + m_ui.helper.height() / 2);
            $(elementBehindTheHelper).addClass("getting-hovered-by-helper").css('box-shadow', '2px 1px 12px 10px lightgreen');
            $(elementBehindTheHelper).droppable({
                iframeFix: true,
                drop: function(event, ui){
                    $(event.target).prepend($('.tester'))
                }
            });
        }
    }, 500);
}});