code: function preDropCleanup() {
                  window.onmousewheel = window.document.onmousewheel = null;
                  $(window).off(".wsvdragging");
                  if (dragged) {
                      $workingFilesContainer.removeClass("dragging");
                      $workingFilesContainer.find(".drag-show-as-selected").removeClass("drag-show-as-selected");
                      endScroll($el);
                      // re-activate the views (adds the "active" class to the view that was previously active)
                      _deactivateAllViews(false);
                      // turn scroll wheel back on
                      $ghost.remove();
                      $el.css("opacity", "");
  
                      if ($el.next().length === 0) {
                          scrollCurrentViewToBottom();
                      }
                  }
              }
docs: Close down the drag operation