This function can be used to "chain" filters, by saving the existing filter
before replacing it with a function that will call that saved filter.
\param filter the current callback function will be stored here.
\param userdata the pointer that is passed to the current event filter will
be stored here.
\returns true on success or false if there is no event filter set.
\threadsafety It is safe to call this function from any thread.
\since This function is available since SDL 3.2.0.
Query the current event filter.
This function can be used to "chain" filters, by saving the existing filter before replacing it with a function that will call that saved filter.
\param filter the current callback function will be stored here. \param userdata the pointer that is passed to the current event filter will be stored here. \returns true on success or false if there is no event filter set.
\threadsafety It is safe to call this function from any thread.
\since This function is available since SDL 3.2.0.
\sa SDL_SetEventFilter