Navigation: a long tab fits its strip and cuts its label

Co-Authored-By: Claude <noreply@anthropic.com>

src/navigation/tabs.rs

@@ -182,6 +182,7 @@ impl RenderOnce for Tabs {
                 let value = tab.value.clone();
                 div()
                     .id(("tab", ix))
+                    .debug_selector(move || format!("tab-{ix}"))
                     .role(Role::Tab)
                     .aria_selected(on)
                     .aria_label(tab.label.clone())
@@ -231,7 +232,10 @@ impl RenderOnce for Tabs {
                     .when(compact, |item| {
                         item.tooltip(Tooltip::text(tab.label.clone()))
                     })
-                    .when(!compact, |item| item.child(tab.label.clone()))
+                    .when(axis == Axis::Horizontal, |item| item.max_w_full())
+                    .when(!compact, |item| {
+                        item.child(div().min_w_0().truncate().child(tab.label.clone()))
+                    })
                     .when_some(tab.note.clone().filter(|_| !compact), |item, note| {
                         item.child(div().text_color(colors.fg_subtle).child(note))
                     })

src/navigation/tests/tabs.rs

@@ -185,12 +185,14 @@ struct Sheets {
     chosen: SharedString,
     clicked: Option<SharedString>,
     width: f32,
+    long: bool,
 }
 
 impl Render for Sheets {
     fn render(&mut self, _: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
         let view = cx.entity();
-        let tabs = (0..30).map(|ix| Choice::new(format!("s{ix}"), format!("Sheet {ix}")));
+        let tail = if self.long { "W".repeat(40) } else { String::new() };
+        let tabs = (0..30).map(|ix| Choice::new(format!("s{ix}"), format!("Sheet {ix}{tail}")));
         div()
             .w(px(self.width))
             .child(
@@ -218,6 +220,7 @@ fn a_wide_strip_scrolls_its_chosen_tab_in_and_the_wheel_reaches_the_rest(cx: &mu
         chosen: "s29".into(),
         clicked: None,
         width: 300.0,
+        long: false,
     });
     settle(cx);
     assert!(
@@ -252,6 +255,7 @@ fn a_strip_that_narrows_keeps_its_chosen_tab_in_view(cx: &mut TestAppContext) {
         chosen: "s29".into(),
         clicked: None,
         width: 700.0,
+        long: false,
     });
     settle(cx);
     view.update(cx, |view, cx| {
@@ -265,3 +269,18 @@ fn a_strip_that_narrows_keeps_its_chosen_tab_in_view(cx: &mut TestAppContext) {
     let clicked = view.read_with(cx, |view, _| view.clicked.clone());
     assert_eq!(clicked, None, "the chosen tab ends the strip");
 }
+
+#[gpui::test]
+fn a_long_chosen_tab_fits_the_strip(cx: &mut TestAppContext) {
+    setup(cx);
+    let (_view, cx) = cx.add_window_view(|_, _| Sheets {
+        chosen: "s29".into(),
+        clicked: None,
+        width: 250.0,
+        long: true,
+    });
+    settle(cx);
+    let tab = cx.debug_bounds("tab-29").expect("the chosen tab");
+    assert!(tab.left() >= px(0.0), "starts in view: {tab:?}");
+    assert!(tab.right() <= px(250.0), "ends in view: {tab:?}");
+}