Ribbon menu buttons carry their name for accessibility (#1050)

The Breaks, Margins, Orientation, Size, Columns and other drop-down
buttons are custom-painted and never called widget_info, so assistive
tech and automation saw them as unlabelled. Register the tip as the
button's name, as the small buttons already do.

Regression test: the Layout > Breaks menu is reachable and its Page and
Next Page items insert a page break and a section break.

crates/ui-egui/src/widgets.rs

@@ -298,6 +298,7 @@ pub fn menu_button(
         resp
     };
     let resp = resp.on_hover_text(tip);
+    resp.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::Button, on, tip));
     if !on {
         return;
     }

crates/ui-egui/tests/breaks_menu.rs

@@ -0,0 +1,60 @@
+//! The ribbon's Breaks menu: its controls carry a name, and each item inserts the break it says.
+
+use serde_json::json;
+use wordcraft_engine::Session;
+use wordcraft_ui_egui::{Services, WordApp};
+
+/// A WordCraft window on the Layout tab, ready for ribbon clicks.
+fn layout_tab() -> egui_kittest::Harness<'static, WordApp> {
+    let app = WordApp::new(Session::new(wordcraft_doc::Document::from_text("one\ntwo")), Services::default());
+    let mut h = egui_kittest::Harness::builder().with_size(egui::vec2(1440.0, 900.0)).build_ui_state(
+        |ui, app: &mut WordApp| {
+            let ctx = ui.ctx().clone();
+            app.logic(&ctx);
+            app.ui(ui);
+        },
+        app,
+    );
+    for _ in 0..6 {
+        h.step();
+    }
+    h.state_mut().run("ui.tab", json!({"tab": "Layout"})).unwrap();
+    for _ in 0..3 {
+        h.step();
+    }
+    h
+}
+
+/// Open the ribbon's Breaks menu and click the item labelled `item`.
+fn click_break(h: &mut egui_kittest::Harness<'static, WordApp>, item: &str) {
+    use egui_kittest::kittest::{NodeT, Queryable};
+    h.get_by_role_and_label(egui::accesskit::Role::Button, "Breaks").click();
+    for _ in 0..3 {
+        h.step();
+    }
+    h.query_all(egui_kittest::kittest::By::new().role(egui::accesskit::Role::Button))
+        .find(|n| n.accesskit_node().label().as_deref().map(str::trim) == Some(item))
+        .unwrap_or_else(|| panic!("the {item} item is in the Breaks menu"))
+        .click();
+    for _ in 0..3 {
+        h.step();
+    }
+}
+
+#[test]
+fn page_break_from_the_menu_adds_a_page() {
+    let mut h = layout_tab();
+    let before = h.state_mut().session.layout().pages.len();
+    click_break(&mut h, "Page");
+    let after = h.state_mut().session.layout().pages.len();
+    assert!(after > before, "the menu Page break added a page (was {before}, now {after})");
+}
+
+#[test]
+fn section_break_from_the_menu_splits_sections() {
+    let mut h = layout_tab();
+    let before = h.state_mut().session.doc.sections().len();
+    click_break(&mut h, "Next Page");
+    let after = h.state_mut().session.doc.sections().len();
+    assert!(after > before, "the menu section break added a section (was {before}, now {after})");
+}