Settings: controls give way, notices fold, and every edit needs its owner

A settings row's control slot shrinks to the box, so a control's text
wraps and a palette's row folds; the font size's sample wraps in a plain
block. A notice's boxes carry their channel's name and fold under the
kind's name when narrow. canvas::panel::editing takes the owner's
handler itself: the design panels, the structure editor, the index
manager and the privacy, notice and startup settings take theirs at
render and fail loud without one. Apply fails loud if pressed while the
proxy does not read. Tests cover Apply resting on a bad port, the way
back resting at the default size and a box pressed off.

src/devtools/structure.rs

@@ -123,7 +123,10 @@ impl TableStructureEditor {
 
 impl RenderOnce for TableStructureEditor {
     fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
-        let (id, fields, on_change) = (self.id, self.fields, &self.on_change);
+        let on_change = self
+            .on_change
+            .unwrap_or_else(|| panic!("table structure editor {:?} has no on_change", self.id));
+        let (id, fields, on_change) = (self.id, self.fields, &on_change);
         let room = window.use_keyed_state((id.clone(), "room"), cx, |_, _| Room::default());
         let rem = window.rem_size();
         let theme = cx.theme();
@@ -336,6 +339,8 @@ impl IndexManager {
 
 impl RenderOnce for IndexManager {
     fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
+        let on_create = self.on_create.expect("an index manager needs on_create");
+        let on_drop = self.on_drop.expect("an index manager needs on_drop");
         let id = self.id;
         let draft = window.use_keyed_state((id.clone(), "draft"), cx, |window, cx| Draft {
             name: cx.new(|cx| TextInput::new(window, cx).placeholder("Index name")),
@@ -345,7 +350,7 @@ impl RenderOnce for IndexManager {
         });
         let theme = cx.theme();
         let rows = self.indexes.iter().map(|index| {
-            let (name, on_drop) = (index.name.clone(), self.on_drop.clone());
+            let (name, on_drop) = (index.name.clone(), on_drop.clone());
             div()
                 .flex()
                 .items_center()
@@ -391,9 +396,7 @@ impl RenderOnce for IndexManager {
                             .tooltip("Drop the index")
                             .on_click(move |_, window, cx| {
                                 log::info!("index manager: drop {name}");
-                                if let Some(on_drop) = &on_drop {
-                                    on_drop(&name, window, cx);
-                                }
+                                on_drop(&name, window, cx);
                             }),
                         ),
                 )
@@ -407,7 +410,6 @@ impl RenderOnce for IndexManager {
         );
         let ready = !name.read(cx).text().trim().is_empty() && !picked.is_empty();
         let [chose, flipped, pick_method, made] = [(); 4].map(|_| draft.clone());
-        let on_create = self.on_create;
         div()
             .flex()
             .flex_col()
@@ -487,9 +489,7 @@ impl RenderOnce for IndexManager {
                                     index
                                 });
                                 log::info!("index manager: create {}", index.name);
-                                if let Some(on_create) = &on_create {
-                                    on_create(index, window, cx);
-                                }
+                                on_create(index, window, cx);
                             }),
                     ),
             )

src/devtools/tests/mod.rs

@@ -204,13 +204,16 @@ fn another_engine_brings_its_port(cx: &mut TestAppContext) {
 fn narrow(_: &Bench, _: &mut Window, _: &mut App, _: Entity<Bench>) -> AnyElement {
     div()
         .w(px(280.0))
-        .child(TableStructureEditor::new(
-            "structure",
-            [
-                Field::new("user_id", "timestamptz"),
-                Field::new("total", "numeric"),
-            ],
-        ))
+        .child(
+            TableStructureEditor::new(
+                "structure",
+                [
+                    Field::new("user_id", "timestamptz"),
+                    Field::new("total", "numeric"),
+                ],
+            )
+            .on_change(|_, _, _| {}),
+        )
         .into_any_element()
 }