Add Modal::has_focus and introduce a ModalHandle trait object

crates/picker/src/picker.rs

@@ -25,6 +25,7 @@ pub struct Picker<D: PickerDelegate> {
     theme: Arc<Mutex<Box<dyn Fn(&theme::Theme) -> theme::Picker>>>,
     confirmed: bool,
     pending_update_matches: Task<Option<()>>,
+    has_focus: bool,
 }
 
 pub trait PickerDelegate: Sized + 'static {
@@ -140,13 +141,22 @@ impl<D: PickerDelegate> View for Picker<D> {
     }
 
     fn focus_in(&mut self, _: AnyViewHandle, cx: &mut ViewContext<Self>) {
+        self.has_focus = true;
         if cx.is_self_focused() {
             cx.focus(&self.query_editor);
         }
     }
+
+    fn focus_out(&mut self, _: AnyViewHandle, _: &mut ViewContext<Self>) {
+        self.has_focus = false;
+    }
 }
 
 impl<D: PickerDelegate> Modal for Picker<D> {
+    fn has_focus(&self) -> bool {
+        self.has_focus
+    }
+
     fn dismiss_on_event(event: &Self::Event) -> bool {
         matches!(event, PickerEvent::Dismiss)
     }
@@ -191,6 +201,7 @@ impl<D: PickerDelegate> Picker<D> {
             theme,
             confirmed: false,
             pending_update_matches: Task::ready(None),
+            has_focus: false,
         };
         this.update_matches(String::new(), cx);
         this