Seems to be Windows only issue. If the pointer type of a smart pointer is of the base class, Qt Creator does not directly show members of the deriving class. Instead one has to navigate through d_ptr to q_ptr to see those.

To reproduce, put breakpoint on the aboutQt() line in attached example and run in debugger. Expanding p3 shows the members directly, but p4 does not. However p1 and p2 both look nice.