I want to move an item from the corkboard to the binder by dragging and dropping.
If the item has no sub-items, then it becomes semi-transparent over the binder so that I can still see the binder layout below - and so I know when to drop.
But if the dragged item has no sub-items, then it stays solid, and so the binder is not visible, and I can't see the target layout below to know when to drop.