Well, if I need pointers, I can use FreeBasic (it has pointers)
Anyway, I think that many people here misunderstood my post: I am not asking for a feature! I only wanted to show a quirk of QBasic and GWBasic: since QB64 is aimed to be a perfect retrocompatible language (Galleon talked about some deprecated features, like KEY ON/ KEY OFF, or like the old OPEN syntax used in GWBasic), I tried to show another, less known one (that makes in some cases QBasic incompatible with GWBasic).
DEF FN has many other problems: in FreeBasic, for example, it hasn't been inplemented because it would have broken compatibility with all names starting with FN ("FName", for example).