Reported when the listview has at least one group in its ‘DropAccept’ list and an item from this source is being dragged over it. The message reports (item-index in your ŒIO)(mode)(menu)(token from drag source)(group1 of source)(group2 ...) as an n-element vector. In the message, mode is 0 for move, 1 for copy; menu is 0 for a normal drop, 1 for a menu request (right-button drag). You may reject the event – otherwise the list item will be drop-highlighted.