rust-sdl | SDL bindings for Rust | Media library

The documentation you are reading is is not for the version you are using. Build it yourself (cargo doc --open) or view it on docs.rs.

That function was added recently and has not been released yet. Perhaps you should file an issue for the authors of the crate to let them know that having documentation that doesn't correspond to any released code is confusing.

In the meantime, you can use a git dependency if you really need it.

The cloned sender has the same type as original sender, so it is still not Sync. add_timer function wants a closure which is Sync, so you need to wrap sender in Mutex which makes your sender safe to share between threads.