shiftDirection [Deprecated]
Defines the direction for selecting consecutive groups of items when holding SHIFT.
Normally, holding the SHIFT key whilst selecting an item will cause all items preceding that item up to the previous selected item (or the first item if there isn't one) to be selected.
You can reverse this behaviour by setting the shiftDirection option to "reverse".
This will cause all items proceeding that item up to the next selected item (or the last item if there isn't one) to be selected.
