virtual void CalcUnscrolledPosition(int x, int y, int *xx, int *yy) const;
virtual void CalcScrolledPosition(int x, int y, int *xx, int *yy) const;
virtual void CalcUnscrolledPosition(int x, int y, int *xx, int *yy) const;
virtual void CalcScrolledPosition(int x, int y, int *xx, int *yy) const;