R5.7: Gitea #1, ElyShow's slide strip scrolls with the wheel; R1 PASS

The strip's list sat in a ContextMenu host with no size, so it grew
with its content and never overflowed. The host now fills its column,
as ElyPDF's do; a 24-slide test wheels to the last slide.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

apps/ely-show/src/slides.rs

@@ -234,6 +234,7 @@ impl Render for Strip {
                 let label = format!("{} {}", part + 1, slide.name);
                 div()
                     .id(("show-slide", part))
+                    .debug_selector(move || format!("show-slide-{part}"))
                     .tab_index(0)
                     .focus_ring(cx)
                     .flex()
@@ -301,6 +302,7 @@ impl Render for Strip {
             .children(slides);
         div()
             .size_full()
-            .child(ContextMenu::new("show-strip-menu", popup(cx)).child(list))
+            // A sized host lets the list overflow and scroll.
+            .child(ContextMenu::new("show-strip-menu", popup(cx)).size_full().child(list))
     }
 }

apps/ely-show/src/tests.rs

@@ -18,6 +18,7 @@ mod play_more;
 mod play_time;
 mod review;
 mod slides;
+mod strip;
 
 /// An unrendered Deck over a fresh worker, if LOK exists.
 pub(super) fn deck(cx: &mut TestAppContext, dir: &Path) -> Option<Entity<Deck>> {

apps/ely-show/src/tests/strip.rs

@@ -0,0 +1,47 @@
+use gpui::{Entity, ScrollDelta, ScrollWheelEvent, TestAppContext, VisualTestContext, point, px};
+
+use super::objects::blank;
+use super::{counts, settle, update};
+use crate::slides::Strip;
+
+/// The slide strip alone in a window.
+struct Host(Entity<Strip>);
+
+impl gpui::Render for Host {
+    fn render(&mut self, _: &mut gpui::Window, _: &mut gpui::Context<Self>) -> impl gpui::IntoElement {
+        use gpui::{ParentElement as _, Styled as _};
+        gpui::div().size_full().child(self.0.clone())
+    }
+}
+
+#[test]
+fn the_wheel_scrolls_the_strip_to_its_last_slide() {
+    let dir = tempfile::tempdir().expect("a temp dir");
+    let mut cx = TestAppContext::single();
+    let Some(deck) = blank(&mut cx, dir.path()) else {
+        return eprintln!("SKIP: no LOK build");
+    };
+    for n in 2..=24 {
+        update(&mut cx, &deck, |deck, cx| deck.object_command("slide.insert", &[], cx));
+        settle(&cx, |app| counts(app, &deck).0 == n);
+    }
+    let strip = cx.update(|app| deck.read(app).strip.clone());
+    let window = cx.add_window(|_, _| Host(strip));
+    let mut shown = VisualTestContext::from_window(window.into(), &cx);
+    shown.run_until_parked();
+    let height = shown.update(|window, _| window.viewport_size().height);
+    let last = |shown: &mut VisualTestContext| shown.debug_bounds("show-slide-23").expect("the last slide is laid out");
+    let before = last(&mut shown);
+    assert!(before.bottom() > height, "the strip is longer than the window");
+    let at = point(before.left() + px(20.0), height / 2.0);
+    for _ in 0..20 {
+        shown.simulate_event(ScrollWheelEvent {
+            position: at,
+            delta: ScrollDelta::Pixels(point(px(0.0), px(-1000.0))),
+            ..Default::default()
+        });
+        shown.run_until_parked();
+    }
+    let after = last(&mut shown);
+    assert!(after.bottom() <= height, "the last slide is in view: {after:?}");
+}