Fix cursor positioning after InOut widget state change

When the InOut changes state and gets hidden as a result, specifically,
we need to make sure to redraw its parent widget. That is necessary,
because said parent (or one of its children) may want to set the cursor
position now that the InOut widget is no longer active.
To that end, this change adjusts the InOut widget's change_state()
method to emit a message indicating an update of the parent, not the
InOut widget itself.

src/ui/in_out.rs

@@ -116,7 +116,13 @@ impl InOutAreaData {
   }
 
   /// Conditionally change the `InOut` state of the widget.
-  fn change_state(&mut self, id: Id, in_out: Option<InOut>) -> Option<Message> {
+  ///
+  /// # Notes
+  /// `parent` should be the `Id` of the parent widget. We should make
+  /// sure to always update the parent widget (as opposed to the `InOut`
+  /// widget itself), because it may want to set the cursor in response
+  /// to this widget being hidden, for example.
+  fn change_state(&mut self, parent: Id, in_out: Option<InOut>) -> Option<Message> {
     // We received a request to change the state. Unconditionally bump
     // the generation it has, irrespective of whether we actually change
     // it (which we don't, if the new state is equal to what we already
@@ -126,10 +132,10 @@ impl InOutAreaData {
     match in_out {
       Some(in_out) if in_out != *self.in_out.get() => {
         self.in_out.set(in_out);
-        Some(Message::updated(id))
+        Some(Message::updated(parent))
       },
       Some(..) => None,
-      None => Some(Message::updated(id)),
+      None => Some(Message::updated(parent)),
     }
   }
 }
@@ -158,6 +164,8 @@ impl InOutArea {
     event: Option<&'f Event>,
   ) -> Pin<Box<dyn Future<Output = Option<Event>> + 'f>> {
     Box::pin(async move {
+      // SANITY: We know that this dialog has a parent.
+      let parent = cap.parent_id(widget.id()).unwrap();
       let data = cap
         .data_mut(widget.id())
         .downcast_mut::<InOutAreaData>()
@@ -179,9 +187,9 @@ impl InOutArea {
         // between pre- and post-hook.
         if data.clear_gen.take() == Some(data.in_out.gen) {
           match data.in_out.get() {
-            InOut::Saved | InOut::Search(_) | InOut::Error(_) => data
-              .change_state(widget.id(), Some(InOut::Clear))
-              .into_event(),
+            InOut::Saved | InOut::Search(_) | InOut::Error(_) => {
+              data.change_state(parent, Some(InOut::Clear)).into_event()
+            },
             InOut::Input(..) | InOut::Clear => None,
           }
         } else {
@@ -197,8 +205,10 @@ impl InOutArea {
     cap: &mut dyn MutCap<Event, Message>,
     string: Option<String>,
   ) -> Option<Message> {
+    // SANITY: We know that this dialog has a parent.
+    let parent = cap.parent_id(self.id).unwrap();
     let data = self.data_mut::<InOutAreaData>(cap);
-    let result1 = data.change_state(self.id, Some(InOut::Clear));
+    let result1 = data.change_state(parent, Some(InOut::Clear));
     let widget = self.restore_focus(cap);
     let message = if let Some(s) = string {
       Message::EnteredText(s)
@@ -234,6 +244,8 @@ impl Handleable<Event, Message> for InOutArea {
   async fn handle(&self, cap: &mut dyn MutCap<Event, Message>, event: Event) -> Option<Event> {
     match event {
       Event::Key(key, raw) => {
+        // SANITY: We know that this dialog has a parent.
+        let parent = cap.parent_id(self.id).unwrap();
         let data = self.data_mut::<InOutAreaData>(cap);
         let text = if let InOut::Input(text) = data.in_out.get_mut() {
           text
@@ -244,7 +256,7 @@ impl Handleable<Event, Message> for InOutArea {
         let message = match text.handle_key(key, &raw) {
           InputResult::Completed(text) => self.finish_input(cap, Some(text)).await,
           InputResult::Canceled => self.finish_input(cap, None).await,
-          InputResult::Updated => data.change_state(self.id, None),
+          InputResult::Updated => data.change_state(parent, None),
           InputResult::Unchanged => {
             data.in_out.bump();
             None
@@ -265,8 +277,10 @@ impl Handleable<Event, Message> for InOutArea {
           self.make_focused(cap);
         };
 
+        // SANITY: We know that this dialog has a parent.
+        let parent = cap.parent_id(self.id).unwrap();
         let data = self.data_mut::<InOutAreaData>(cap);
-        data.change_state(self.id, Some(in_out))
+        data.change_state(parent, Some(in_out))
       },
       #[cfg(all(test, not(feature = "readline")))]
       Message::GetInOut => {