+ void set_position_internal (framepos_t pos, bool allow_bbt_recompute, const int32_t sub_num);
+ void set_length_internal (framecnt_t len, const int32_t sub_num);
+ void set_start_internal (framecnt_t, const int32_t sub_num);
+ void trim_to_internal (framepos_t position, framecnt_t length, const int32_t sub_num);
+ void update_length_beats (const int32_t sub_num);