Android : Drag+Drop onto GridView or GridView's item (Drag end ignored)

I am trying to allow a user to drag and drop an object onto a Grid View to put that item into the grid. OR to drag onto an existing item on the grid to combine them.

I have the drag listeners working. Making the controls blue when a drag starts, green when the item is hovering开发者_开发百科 over them then back again once the drag finished.

However as soon as there are child items in the Grid the DRAG_ACTION_ENDED isn't called on the GridView. It's children still receive it so I am able to un-highlight them but the GridView remains highlighted.

Any idea why the drag ended event isn't being passed through?