feat(dropdown): add Id support with custom close, open operations

src/widget/dropdown/operation.rs

@@ -0,0 +1,72 @@
+// Copyright 2025 System76 <info@system76.com>
+// SPDX-License-Identifier: MPL-2.0 AND MIT
+//! Operate on dropdown widgets.
+
+use super::State;
+use iced::Rectangle;
+use iced_core::widget::{Id, Operation};
+
+pub trait Dropdown {
+    fn close(&mut self);
+    fn open(&mut self);
+}
+
+/// Produces a [`Task`] that closes a [`Dropdown`] popup.
+pub fn close<T>(id: Id) -> impl Operation<T> {
+    struct Close(Id);
+
+    impl<T> Operation<T> for Close {
+        fn custom(&mut self, state: &mut dyn std::any::Any, id: Option<&Id>) {
+            if id.map_or(true, |id| id != &self.0) {
+                return;
+            }
+
+            let Some(state) = state.downcast_mut::<State>() else {
+                return;
+            };
+
+            state.close();
+        }
+
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            _bounds: Rectangle,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self)
+        }
+    }
+
+    Close(id)
+}
+
+/// Produces a [`Task`] that opens a [`Dropdown`] popup.
+pub fn open<T>(id: Id) -> impl Operation<T> {
+    struct Open(Id);
+
+    impl<T> Operation<T> for Open {
+        fn custom(&mut self, state: &mut dyn std::any::Any, id: Option<&Id>) {
+            if id.map_or(true, |id| id != &self.0) {
+                return;
+            }
+
+            let Some(state) = state.downcast_mut::<State>() else {
+                return;
+            };
+
+            state.open();
+        }
+
+        fn container(
+            &mut self,
+            _id: Option<&Id>,
+            _bounds: Rectangle,
+            operate_on_children: &mut dyn FnMut(&mut dyn Operation<T>),
+        ) {
+            operate_on_children(self)
+        }
+    }
+
+    Open(id)
+}