typeDrag/drop payload type identifier (at most 32 characters); names starting with _ are reserved.
flagsImGuiDragDropFlags options controlling this operation; combine compatible flag bits with |.
Borrowed matching payload, or null when none is accepted. With ImGuiDragDropFlags.AcceptBeforeDelivery, check Payload_IsDelivery(payload) on a non-null result before committing the drop.
Accept contents of a given type.