The UI sense (drag-and-drop) is now dominant over the older literal 'to haul/drag'. Compare 拖 (simple 'to pull'), 拖动 (to drag, slightly more generic), and 拖拽 (the specific UI action).
memory
拖 (to pull/drag) + 拽 (to yank/tug), two near-synonyms bonded together for emphasis, like English 'haul and drag'.
