typedef bool (*tts_config_supported_voice_cb)(const char* engine_id, const char* language, int type, void* user_data);
typedef void (*tts_config_engine_changed_cb)(const char* engine_id, const char* setting,
typedef bool (*tts_config_supported_voice_cb)(const char* engine_id, const char* language, int type, void* user_data);
typedef void (*tts_config_engine_changed_cb)(const char* engine_id, const char* setting,