[fpc-pascal] Is is impossible to extend a generic class in fpc 2..6.4?

[Dennis Poon]

Is it impossible to extend a generic class?
I tried to extend a generic class "TFPGMap" in fpl unit.

its original definition is:
      generic TFPGMap<TKey, TData> = class(TFPSMap)

I want to extend it by:
   generic TMyMap<TKey, TData>=class(TFPGMap )
   end;

I got this error: Generics without specialization cannot be used as a 
type for a variable


Then I tried:
   generic TMyMap<TKey, TData>=class(generic TFPGMap<TKey, TData> )
   end;

but I got Error: Identifier not found "generic"


I know it was not possible in the past. Just want to know whether it is 
still not possible in fpc 2.6.4.

Thanks.

Dennis