Fix bug of calculator. - calc can not handle button press event. - It caused by miss-understanding event_t::cur_tgt. It is a subject, not a shape that calc think. - event_t::cur_tgt::obj is a shape that calc want. It is a the subject that the subject stands for.

#ifndef __MB_H_
#define __MB_H_

#include "mb_types.h"
#include "mb_redraw_man.h"
#include "mb_X_supp.h"
#include "mb_animate.h"
#include "mb_shapes.h"

#endif /* __MB_H_ */