Sets the values of this object's subentity traits, and returns with the calling object's subentity traits.
kDrawableNone.
When overriding subSetAttributes(), you must OR (|) the return value of ::subSetAttributes(pTraits) with any flags you add.
A derived class may not remove flags for any reason.
The default implementation does nothing but returns kDrawableNone. This function can be overridden in custom classes.