The `event::Source::Any` variant is a bitmask from the C API which probably shouldn't be exposed like this in the Rust API

[rib]

Since the Source is currently bound as a enum, I wouldn't expect it to contain bitmask values from the C API.

Maybe if it were instead exposed via bitflags::bitflags! {} it could be good to expose this, but I think sticking with an enum, with mutually exclusive source variants, seems appropriate here.

For the case where the source is unknown it could potentially be useful to have an .any() method (or similar) that would be able to internally use this bitmask against the unknown source value.