Make iced_native subscription input opaque

native/src/subscription/events.rs

@@ -0,0 +1,23 @@
+use crate::{
+    subscription::{EventStream, Recipe},
+    Event, Hasher,
+};
+
+pub struct Events;
+
+impl Recipe<Hasher, EventStream> for Events {
+    type Output = Event;
+
+    fn hash(&self, state: &mut Hasher) {
+        use std::hash::Hash;
+
+        std::any::TypeId::of::<Self>().hash(state);
+    }
+
+    fn stream(
+        self: Box<Self>,
+        event_stream: EventStream,
+    ) -> futures::stream::BoxStream<'static, Self::Output> {
+        event_stream
+    }
+}