Found this online: https://www.refheap.com/73581
(defn allow-drop [e]
(.preventDefault e)) ;; because DnD in HTMl5 is crazy...
:draggable true ; -> otherwise the browser won't let you drag it
:on-drag-over allow-drop
:on-drag-enter allow-drop
:on-drag-start #(.setData (.-dataTransfer %) "text/plain" "") ;; for Firefox. You MUST set something as data.
:on-drag-end some-action
:on-drop some-other-action