Filter
The Filter predicate marks certain items as non-draggable. Try dragging the red item - it
can't be picked up. The other items can still be dragged past it, which shifts it along by one.
Item 1
Item 2
Item 3
Filtered (locked)
Item 4
Item 5
Order: Item 1, Item 2, Item 3, Filtered (locked), Item 4, Item 5