dropdown: Support change options for the dropdown (#824)

crates/story/src/dropdown_story.rs

@@ -138,21 +138,24 @@ impl DropdownStory {
                     .title_prefix("UI: ")
                 }),
                 simple_dropdown2: cx.new(|cx| {
-                    Dropdown::new(
+                    let mut dropdown =
-                        "string-list2",
+                        Dropdown::new("string-list2", SearchableVec::new(vec![]), None, window, cx)
+                            .small()
+                            .placeholder("Language")
+                            .title_prefix("Language: ");
+
+                    dropdown.set_items(
                         SearchableVec::new(vec![
                             "Rust".into(),
                             "Go".into(),
                             "C++".into(),
                             "JavaScript".into(),
                         ]),
-                        None,
                         window,
                         cx,
-                    )
+                    );
-                    .small()
+
-                    .placeholder("Language")
+                    dropdown
-                    .title_prefix("Language: ")
                 }),
                 simple_dropdown3: cx.new(|cx| {
                     Dropdown::new("string-list3", Vec::<SharedString>::new(), None, window, cx)

crates/ui/src/dropdown.rs

@@ -600,6 +600,16 @@ where
             })
             .child(title)
     }
+
+    /// Set the items for the dropdown.
+    pub fn set_items(&mut self, items: D, _: &mut Window, cx: &mut Context<Self>)
+    where
+        D: DropdownDelegate + 'static,
+    {
+        self.list.update(cx, |list, _| {
+            list.delegate_mut().delegate = items;
+        });
+    }
 }
 
 impl<D> Sizable for Dropdown<D>