Rationale same as vbi_is_cached().
This function is deprecated. Use vbi_capture_dvb_new2() instead.
Replaces all existing handlers with this handler function, ignoring user_data. Use vbi_event_handler_register() in new code.
At the moment pages can only be added to the cache but not removed unless the decoder is reset. That will change, making the result volatile in a multithreaded environment.