class B: public TopWindow {
public:
  enum tp
  {
    TPA,
    TPB
  };
  void set(enum tp);
  ...
}
class A: public TopWindow {
...
private:
  B *b;
  void Button_A()
  {
	b->PostCallback(callback1(b, &B::set, B::TPA));
  }
...
}