Revert window::close producing a window::Id

Instead, subscribing to `window::close_events` is
preferable; since most use cases will want to react
to the user closing a window as well.

examples/events/src/main.rs

@@ -37,7 +37,7 @@ impl Events {
             }
             Message::EventOccurred(event) => {
                 if let Event::Window(window::Event::CloseRequested) = event {
-                    window::get_latest().and_then(window::close).discard()
+                    window::get_latest().and_then(window::close)
                 } else {
                     Task::none()
                 }
@@ -47,9 +47,7 @@ impl Events {
 
                 Task::none()
             }
-            Message::Exit => {
+            Message::Exit => window::get_latest().and_then(window::close),
-                window::get_latest().and_then(window::close).discard()
-            }
         }
     }
 

examples/exit/src/main.rs

@@ -20,9 +20,7 @@ enum Message {
 impl Exit {
     fn update(&mut self, message: Message) -> Task<Message> {
         match message {
-            Message::Confirm => {
+            Message::Confirm => window::get_latest().and_then(window::close),
-                window::get_latest().and_then(window::close).discard()
-            }
             Message::Exit => {
                 self.show_confirm = true;
 

runtime/src/window.rs

@@ -24,7 +24,7 @@ pub enum Action {
     Open(Id, Settings, oneshot::Sender<Id>),
 
     /// Close the window and exits the application.
-    Close(Id, oneshot::Sender<Id>),
+    Close(Id),
 
     /// Gets the [`Id`] of the oldest window.
     GetOldest(oneshot::Sender<Option<Id>>),
@@ -230,8 +230,8 @@ pub fn open(settings: Settings) -> (Id, Task<Id>) {
 }
 
 /// Closes the window with `id`.
-pub fn close(id: Id) -> Task<Id> {
+pub fn close<T>(id: Id) -> Task<T> {
-    task::oneshot(|channel| crate::Action::Window(Action::Close(id, channel)))
+    task::effect(crate::Action::Window(Action::Close(id)))
 }
 
 /// Gets the window [`Id`] of the oldest window.

winit/src/program.rs

@@ -1211,10 +1211,9 @@ fn run_action<P, C>(
 
                 *is_window_opening = true;
             }
-            window::Action::Close(id, channel) => {
+            window::Action::Close(id) => {
                 let _ = window_manager.remove(id);
                 let _ = ui_caches.remove(&id);
-                let _ = channel.send(id);
 
                 events.push((
                     id,