Tab overflow list scrolls to every open document (#4017)

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

crates/ui-egui/src/chrome.rs

@@ -512,7 +512,9 @@ pub fn doc_tabs(app: &mut VectorcraftApp, ui: &mut Ui) {
         x += w;
     }
     crate::document_drag::finish_tabs(ui.ctx(), hovering_art);
-    // The » button: every open document, the active one checked.
+    // The » button: every open document, the active one checked. The list scrolls once it
+    // reaches the bottom of the window, so every document of a large session stays reachable
+    // (#4017).
     if overflow {
         let more = egui::Rect::from_min_max(egui::pos2(strip.right() - MORE, strip.top()), egui::pos2(strip.right(), strip.bottom() - 1.0));
         let resp = ui.interact(more, ui.scope_id().with("tabs-more"), Sense::click());
@@ -520,12 +522,14 @@ pub fn doc_tabs(app: &mut VectorcraftApp, ui: &mut Ui) {
         icons::paint(ui, "chevrons-right", egui::Rect::from_center_size(more.center(), vec2(14.0, 14.0)), t.text);
         let resp = resp.on_hover_text(tl!("Show all open documents"));
         egui::Popup::menu(&resp).show(|ui| {
-            for (i, (title, _)) in tabs.iter().enumerate() {
-                if widgets::menu_item_name(ui, title, true, Some(i) == active) {
-                    activate = Some(i);
-                    ui.close();
+            widgets::menu_scroll(ui, |ui| {
+                for (i, (title, _)) in tabs.iter().enumerate() {
+                    if widgets::menu_item_name(ui, title, true, Some(i) == active) {
+                        activate = Some(i);
+                        ui.close();
+                    }
                 }
-            }
+            });
         });
     }
     if let Some(i) = close {

crates/ui-egui/src/lib.rs

@@ -173,6 +173,8 @@ mod tests_sysclip_emf;
 #[cfg(test)]
 mod tests_sysclip_probe;
 #[cfg(test)]
+mod tests_tab_overflow;
+#[cfg(test)]
 mod tests_taskbar;
 #[cfg(test)]
 mod tests_transparencygrid;

crates/ui-egui/src/tests_tab_overflow.rs

@@ -0,0 +1,87 @@
+//! The » list of the document tab strip with more documents than fit in the window (#4017).
+
+use egui::{Event, PointerButton, Pos2};
+use serde_json::json;
+use vectorcraft_engine::Session;
+
+use crate::{VectorcraftApp, chrome};
+
+const SIZE: egui::Vec2 = egui::vec2(1000.0, 700.0);
+
+/// Run a tab-strip frame and return the visible texts with their screen rects.
+fn frame(app: &mut VectorcraftApp, ctx: &egui::Context, time: f64, events: Vec<Event>) -> Vec<(String, egui::Rect)> {
+    let mut out = ctx.run_ui(
+        egui::RawInput { screen_rect: Some(egui::Rect::from_min_size(Pos2::ZERO, SIZE)), time: Some(time), events, ..Default::default() },
+        |ui| {
+            egui::CentralPanel::default().show(ui, |ui| chrome::doc_tabs(app, ui));
+        },
+    );
+    out.textures_delta.clear();
+    let screen = egui::Rect::from_min_size(Pos2::ZERO, SIZE);
+    // Texts nested in shape lists too, kept only where their clip rect shows them whole.
+    fn walk(s: &egui::Shape, clip: egui::Rect, v: &mut Vec<(String, egui::Rect)>) {
+        match s {
+            egui::Shape::Text(t) => {
+                let r = egui::Rect::from_min_size(t.pos, t.galley.size());
+                if clip.contains_rect(r) {
+                    v.push((t.galley.text().to_owned(), r));
+                }
+            }
+            egui::Shape::Vec(list) => list.iter().for_each(|s| walk(s, clip, v)),
+            _ => {}
+        }
+    }
+    let mut texts = vec![];
+    for c in &out.shapes {
+        walk(&c.shape, c.clip_rect.intersect(screen), &mut texts);
+    }
+    texts
+}
+
+fn click(at: Pos2, pressed: bool) -> Event {
+    Event::PointerButton { pos: at, button: PointerButton::Primary, pressed, modifiers: Default::default() }
+}
+
+/// Every document of a large session can be picked from the » list: it scrolls instead of running
+/// off the bottom of the window.
+#[test]
+fn the_tab_overflow_list_scrolls_to_its_last_document() {
+    let mut app = VectorcraftApp::new(Session::new(), Default::default());
+    for i in 0..60 {
+        app.run("file.new", json!({"width": 100, "height": 100, "name": format!("Doc {i:02}")})).unwrap();
+    }
+    app.session.set_active(0);
+    app.sync_views();
+    let ctx = egui::Context::default();
+    crate::theme::install_fonts(&ctx);
+    let texts = frame(&mut app, &ctx, 0.0, vec![]);
+    let tab = texts.iter().find(|(t, _)| t.starts_with("Doc 00")).map(|(_, r)| *r).unwrap();
+    // The » button sits at the right end of the strip, level with the tabs.
+    let more = egui::pos2(SIZE.x - 8.0 - 15.0, tab.center().y);
+    frame(&mut app, &ctx, 0.1, vec![Event::PointerMoved(more)]);
+    frame(&mut app, &ctx, 0.15, vec![click(more, true)]);
+    frame(&mut app, &ctx, 0.2, vec![click(more, false)]);
+    frame(&mut app, &ctx, 0.25, vec![]);
+    let texts = frame(&mut app, &ctx, 0.3, vec![]);
+    // The list's rows put a check column before each title; the tabs don't.
+    let row = |texts: &[(String, egui::Rect)], name: &str| texts.iter().find(|(t, _)| !t.starts_with("Doc") && t.contains(name)).map(|(_, r)| *r);
+    let first = row(&texts, "Doc 00").unwrap_or_else(|| panic!("the » list is open: {texts:?}"));
+    assert!(row(&texts, "Doc 59").is_none(), "the last document starts below the bottom of the window");
+    let wheel = Event::MouseWheel {
+        unit: egui::MouseWheelUnit::Point,
+        delta: egui::vec2(0.0, -20000.0),
+        phase: egui::TouchPhase::Move,
+        modifiers: Default::default(),
+        source: egui::MouseWheelSource::Unknown,
+    };
+    frame(&mut app, &ctx, 0.35, vec![Event::PointerMoved(first.center()), wheel]);
+    let mut texts = vec![];
+    for i in 4..40 {
+        texts = frame(&mut app, &ctx, f64::from(i) * 0.1, vec![]);
+    }
+    let last = row(&texts, "Doc 59").unwrap_or_else(|| panic!("the wheel scrolls the list to its last document: {texts:?}")).center();
+    frame(&mut app, &ctx, 4.0, vec![Event::PointerMoved(last)]);
+    frame(&mut app, &ctx, 4.1, vec![click(last, true)]);
+    frame(&mut app, &ctx, 4.2, vec![click(last, false)]);
+    assert_eq!(app.session.active_index(), Some(59), "the last document is picked from the list");
+}