[Gambas-user] Issue 78 in gambas: Illegal optimization / May a method's return value type in a derived class be different from the base class?

[gambas at ...2524...]

Comment #3 on issue 78 by emil.len... at ...626...: Illegal optimization / May  
a method's return value type in a derived class be different from the base  
class?
http://code.google.com/p/gambas/issues/detail?id=78

What is that supposed to mean?
It is allowed to override a function by another function that returns a  
different datatype, but it is not allowed to call such a function of the  
base class, because that can return different datatypes?