docs: function Draggable(el, options) {
        this.options = $.extend({}, defaults, options);
        this.$document = $(document);
        this.$container = $(el);
        this.$dragitems = $(this.options.items, this.$container);
        this.is_dragging = false;
        this.player_min_left = 0 + this.options.offset_left;
        this.id = uniqId();
        this.ns = '.gridster-draggable-' + this.id;
        this.init();
      }