struct mainwindowfieldsptr {
	x::ptr_cast<x::w::container> horizontal_container;
	x::ptr_cast<x::w::container> vertical_container;
	x::ptr_cast<x::w::button> insert_column;
	x::ptr_cast<x::w::button> remove_column;
	x::ptr_cast<x::w::button> insert_row;
	x::ptr_cast<x::w::button> remove_row;

	inline void validate_or_throw_exception() const
	{
		if (!horizontal_container) validation_failed("horizontal_container");
		if (!vertical_container) validation_failed("vertical_container");
		if (!insert_column) validation_failed("insert_column");
		if (!remove_column) validation_failed("remove_column");
		if (!insert_row) validation_failed("insert_row");
		if (!remove_row) validation_failed("remove_row");
	}

	static inline void validation_failed(const char *object_name)
			__attribute__((noreturn))
	{
		throw EXCEPTION("Internal error: object \"" << object_name
				<< "\" was not created.");
	}
};

struct mainwindowfields {
	x::w::container horizontal_container;
	x::w::container vertical_container;
	x::w::button insert_column;
	x::w::button remove_column;
	x::w::button insert_row;
	x::w::button remove_row;

	mainwindowfields(const mainwindowfieldsptr &p)
	: horizontal_container(p.horizontal_container),
	  vertical_container(p.vertical_container),
	  insert_column(p.insert_column),
	  remove_column(p.remove_column),
	  insert_row(p.insert_row),
	  remove_row(p.remove_row)
	{}
};