diff --git a/crates/ui-egui/src/panels/gradient.rs b/crates/ui-egui/src/panels/gradient.rs
index 427cb5f5f..08336673d 100644
--- a/crates/ui-egui/src/panels/gradient.rs
+++ b/crates/ui-egui/src/panels/gradient.rs
@@ -785,450 +785,4 @@ pub fn menu(app: &mut VectorcraftApp, ui: &mut Ui) {
 }
 
 #[cfg(test)]
-mod tests {
-    use egui::{Event, Modifiers, PointerButton};
-    use vectorcraft_engine::Session;
-
-    use super::*;
-
-    #[test]
-    fn offsets_and_json() {
-        assert_eq!(x_to_offset(50.0, 0.0, 200.0), 0.25);
-        assert_eq!(x_to_offset(-5.0, 0.0, 200.0), 0.0);
-        assert_eq!(x_to_offset(500.0, 0.0, 200.0), 1.0);
-        let j = stops_json(&Gradient::default().stops);
-        assert_eq!(j.as_array().unwrap().len(), 2);
-        assert_eq!(j[1]["midpoint"], json!(0.5));
-    }
-
-    #[test]
-    fn dropped_colours_recolour_or_add_an_opaque_stop() {
-        let mut g = Gradient::default();
-        g.stops[1].opacity = 0.5;
-        let red = Color::rgb(1.0, 0.0, 0.0);
-        let (v, i) = drop_color(&g, Some(1), 0.3, red, None);
-        assert_eq!((v.len(), i, v[1].color, v[1].opacity), (2, 1, red, 1.0));
-        let (v, i) = drop_color(&g, None, 0.3, red, None);
-        assert_eq!((v.len(), i, v[1].color, v[1].offset, v[1].opacity), (3, 1, red, 0.3, 1.0));
-    }
-
-    /// In a CMYK document an RGB swatch's color applied to the selected stop or freeform point
-    /// keeps its model, as the swatch applied to a fill does.
-    #[test]
-    fn a_swatch_color_on_a_stop_or_a_point_keeps_its_model_in_a_cmyk_document() {
-        let stops = json!([{"offset": 0, "color": {"c": 0, "m": 0, "y": 0, "k": 0}}, {"offset": 1, "color": {"c": 0, "m": 0, "y": 0, "k": 1}}]);
-        let mut app = app(json!({"gradient": {"stops": stops}}));
-        app.run("file.documentColorMode", json!({"mode": "cmyk"})).unwrap();
-        let orange = Color::rgb8(255, 128, 0);
-        app.run("swatch.new", json!({"name": "Screen", "color": "#ff8000", "keepModel": true})).unwrap();
-        app.run("gradient.selectStop", json!({"index": 1})).unwrap();
-        assert!(recolor_selected(&mut app, orange, &json!({"swatch": "Screen"})));
-        let Paint::Gradient(g) = active_paint(&app) else { panic!("a gradient fill") };
-        assert_eq!(g.gradient.stops[1].color, orange);
-        app.run("paint.editGradient", json!({"kind": "freeform"})).unwrap();
-        app.run("paint.freeform.selectPoint", json!({"index": 1})).unwrap();
-        assert!(recolor_selected(&mut app, orange, &json!({"swatch": "Screen"})));
-        let Paint::Gradient(g) = active_paint(&app) else { panic!("a gradient fill") };
-        assert_eq!(g.freeform.map(|f| f.points[1].color), Some(orange));
-    }
-
-    /// In a CMYK document Add to Swatches and Save to Swatches keep the gradient's RGB stops RGB.
-    #[test]
-    fn a_gradient_saved_as_a_swatch_keeps_its_stops_models_in_a_cmyk_document() {
-        let mut app = app(json!({"color": "#000000"}));
-        app.run("file.documentColorMode", json!({"mode": "cmyk"})).unwrap();
-        let stops = json!([{"offset": 0, "color": "#ff8000"}, {"offset": 1, "color": {"c": 0, "m": 0, "y": 0, "k": 1}}]);
-        app.run("paint.setFill", json!({"gradient": {"stops": stops}, "keepModel": true})).unwrap();
-        let g = current(&app).expect("a gradient fill");
-        let colors = |g: &GradientPaint| g.gradient.stops.iter().map(|s| s.color).collect::<Vec<_>>();
-        assert_eq!(colors(&g), [Color::rgb8(255, 128, 0), Color::cmyk(0.0, 0.0, 0.0, 1.0)]);
-        save_to_swatches(&mut app, &g);
-        let Some(Paint::Gradient(saved)) = app.session.doc().unwrap().doc.swatches.last().map(|w| w.paint.clone()) else {
-            panic!("a gradient swatch")
-        };
-        assert_eq!(colors(&saved), colors(&g));
-    }
-
-    #[test]
-    fn dragged_stops_move_copy_or_swap() {
-        let g = Gradient::default();
-        let (v, i) = dragged_stops(&g.stops, 0, 0.4, false, Some(1));
-        assert_eq!((v.len(), i, v[0].offset), (2, 0, 0.4));
-        let (v, i) = dragged_stops(&g.stops, 0, 0.4, true, None);
-        assert_eq!((v.len(), i, v[1].offset, v[1].color), (3, 1, 0.4, Color::WHITE));
-        let (v, i) = dragged_stops(&g.stops, 0, 1.0, true, Some(1));
-        assert_eq!((v.len(), i, v[0].color, v[1].color), (2, 0, Color::BLACK, Color::WHITE));
-        // Dropped on itself: a copy.
-        assert_eq!(dragged_stops(&g.stops, 0, 0.0, true, Some(0)).0.len(), 3);
-    }
-
-    // ---------- headless frames ----------
-
-    /// A selected rectangle filled with `fill` (`paint.setFill` params).
-    fn app(fill: Value) -> VectorcraftApp {
-        let mut app = VectorcraftApp::new(Session::new(), Default::default());
-        app.run("file.new", json!({"width": 300, "height": 300})).unwrap();
-        app.run("shape.rectangle", json!({"x": 100, "y": 100, "width": 100, "height": 100})).unwrap();
-        app.run("paint.setFill", fill).unwrap();
-        app
-    }
-
-    /// A headless Gradient panel: frames share one context and a clock.
-    struct Panel {
-        ctx: egui::Context,
-        time: f64,
-    }
-
-    impl Panel {
-        fn new() -> Self {
-            let ctx = egui::Context::default();
-            crate::theme::install_fonts(&ctx);
-            Self { ctx, time: 0.0 }
-        }
-
-        /// One frame with `events` (and `modifiers` held); returns the texts drawn and where.
-        fn frame(&mut self, app: &mut VectorcraftApp, events: Vec<Event>, modifiers: Modifiers) -> Vec<(String, Pos2)> {
-            fn texts(s: &egui::Shape, out: &mut Vec<(String, Pos2)>) {
-                match s {
-                    egui::Shape::Text(t) => out.push((t.galley.text().to_string(), t.pos + t.galley.rect.center().to_vec2())),
-                    egui::Shape::Vec(v) => v.iter().for_each(|s| texts(s, out)),
-                    _ => {}
-                }
-            }
-            self.time += 0.1;
-            let mut events = events;
-            events.insert(0, Event::ModifiersChanged(modifiers));
-            let input = egui::RawInput {
-                time: Some(self.time),
-                events,
-                screen_rect: Some(Rect::from_min_size(Pos2::ZERO, vec2(260.0, 600.0))),
-                ..Default::default()
-            };
-            let mut out = self.ctx.run_ui(input, |ui| show(app, ui));
-            out.textures_delta.clear();
-            let mut v = vec![];
-            out.shapes.iter().for_each(|c| texts(&c.shape, &mut v));
-            v
-        }
-
-        /// The rect of the widget keyed `key` (last frame). egui 0.37's `WidgetRect.parent_id` is
-        /// the parent Ui's unstable `unique_id`, not the stable `scope_id` widgets are salted with;
-        /// debug builds remember the `with(key)` that made each id, so match that.
-        fn widget(&self, key: impl std::hash::Hash + std::fmt::Debug + Copy) -> Rect {
-            let suffix = format!(".with({key:?})");
-            self.ctx
-                .viewport(|vp| {
-                    vp.prev_pass.widgets.layers().flat_map(|(_, w)| w.iter()).find(|w| format!("{:?}", w.id).ends_with(&suffix)).map(|w| w.rect)
-                })
-                .expect("widget drawn")
-        }
-
-        fn click(&mut self, app: &mut VectorcraftApp, at: Pos2) -> Vec<(String, Pos2)> {
-            let b = |pressed| Event::PointerButton { pos: at, button: PointerButton::Primary, pressed, modifiers: Modifiers::NONE };
-            self.frame(app, vec![Event::PointerMoved(at), b(true)], Modifiers::NONE);
-            self.frame(app, vec![b(false)], Modifiers::NONE);
-            self.frame(app, vec![], Modifiers::NONE)
-        }
-
-        /// The `size`-square widgets right of `at` on its row (last frame), left to right.
-        fn row_after(&self, at: Pos2, size: f32) -> Vec<Rect> {
-            let mut v: Vec<Rect> = self.ctx.viewport(|vp| {
-                vp.prev_pass
-                    .widgets
-                    .layers()
-                    .flat_map(|(_, w)| w.iter())
-                    .map(|w| w.rect)
-                    .filter(|r| {
-                        (r.width() - size).abs() < 0.5 && (r.height() - size).abs() < 0.5 && (r.center().y - at.y).abs() < 8.0 && r.left() > at.x
-                    })
-                    .collect()
-            });
-            v.sort_by(|a, b| a.left().total_cmp(&b.left()));
-            v.dedup();
-            v
-        }
-
-        /// Press at `from`, move to `to` in steps and release there, with `m` held.
-        fn drag(&mut self, app: &mut VectorcraftApp, from: Pos2, to: Pos2, m: Modifiers) {
-            let b = |at, pressed| Event::PointerButton { pos: at, button: PointerButton::Primary, pressed, modifiers: m };
-            self.frame(app, vec![Event::PointerMoved(from), b(from, true)], m);
-            for k in 1..=4 {
-                self.frame(app, vec![Event::PointerMoved(from + (to - from) * (k as f32 / 4.0))], m);
-            }
-            self.frame(app, vec![b(to, false)], m);
-            self.frame(app, vec![], Modifiers::NONE);
-        }
-    }
-
-    fn fill(app: &VectorcraftApp) -> GradientPaint {
-        match crate::panels::current_paints(app).0 {
-            Paint::Gradient(g) => *g,
-            p => panic!("expected a gradient fill, got {p:?}"),
-        }
-    }
-
-    fn hexes(app: &VectorcraftApp) -> Vec<String> {
-        fill(app).gradient.stops.iter().map(|s| s.color.to_hex()).collect()
-    }
-
-    #[test]
-    fn the_proxy_toggles_fill_and_stroke_and_stays_with_options_hidden() {
-        let mut app = app(json!({"gradient": {}}));
-        let mut p = Panel::new();
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        assert!(texts.iter().any(|(t, _)| t == "Opacity:"));
-        let stroke = p.widget("stroke-proxy");
-        p.click(&mut app, stroke.right_bottom() - vec2(2.0, 2.0));
-        assert!(!app.session.fill_active, "the Stroke proxy came to the front");
-        set_pstate(&p.ctx, HIDE_OPTIONS, true);
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        assert!(!texts.iter().any(|(t, _)| t == "Opacity:" || t == "Type:"), "{texts:?}");
-        let fill = p.widget("fill-proxy");
-        p.click(&mut app, fill.left_top() + vec2(2.0, 2.0));
-        assert!(app.session.fill_active, "the proxy works with the options hidden");
-        p.widget(("grad-stop", 1));
-    }
-
-    #[test]
-    fn the_stroke_buttons_lay_the_gradient_within_along_or_across_the_stroke() {
-        let mut app = app(json!({"gradient": {}}));
-        app.run("paint.setStroke", json!({"gradient": {}, "focus": false})).unwrap();
-        assert!(app.session.fill_active);
-        let mode = |app: &VectorcraftApp| app.session.shown_stroke().unwrap().gradient_mode;
-        let mut p = Panel::new();
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        let label = texts.iter().find(|(t, _)| t == "Stroke:").expect("the Stroke buttons").1;
-        // With the Fill proxy in front they are off.
-        let buttons = p.row_after(label, 22.0);
-        assert_eq!(buttons.len(), 3);
-        p.click(&mut app, buttons[1].center());
-        assert_eq!(mode(&app), StrokeGradientMode::Within);
-        let stroke = p.widget("stroke-proxy");
-        p.click(&mut app, stroke.right_bottom() - vec2(2.0, 2.0));
-        assert!(!app.session.fill_active);
-        for (i, want) in [(1, StrokeGradientMode::Along), (2, StrokeGradientMode::Across), (0, StrokeGradientMode::Within)] {
-            p.click(&mut app, buttons[i].center());
-            assert_eq!(mode(&app), want);
-        }
-        app.run("edit.undo", json!({})).unwrap();
-        assert_eq!(mode(&app), StrokeGradientMode::Across, "one undo step per click");
-    }
-
-    #[test]
-    fn the_dither_box_dithers_the_gradient_fill_and_is_off_for_strokes() {
-        let mut app = app(json!({"gradient": {}}));
-        app.run("paint.setStroke", json!({"gradient": {}, "focus": false})).unwrap();
-        let mut p = Panel::new();
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        let at = texts.iter().find(|(t, _)| t == "Dither").expect("the Dither box").1;
-        p.click(&mut app, at);
-        assert!(fill(&app).gradient.dither, "the fill's gradient is dithered");
-        p.click(&mut app, at);
-        assert!(!fill(&app).gradient.dither, "a second click clears it");
-        app.run("edit.undo", json!({})).unwrap();
-        assert!(fill(&app).gradient.dither, "one undo step per click");
-        // Behind the Stroke proxy the box is dimmed and does nothing.
-        let stroke = p.widget("stroke-proxy");
-        p.click(&mut app, stroke.right_bottom() - vec2(2.0, 2.0));
-        assert!(!app.session.fill_active);
-        let undo = app.session.doc().unwrap().history.undo.len();
-        p.click(&mut app, at);
-        assert_eq!(app.session.doc().unwrap().history.undo.len(), undo, "no edit on the stroke");
-        let Paint::Gradient(st) = app.session.shown_stroke().unwrap().paint.clone() else { panic!("a gradient stroke") };
-        assert!(!st.gradient.dither);
-    }
-
-    #[test]
-    fn the_method_menu_makes_the_gradient_perceptual() {
-        let mut app = app(json!({"gradient": {}}));
-        let mut p = Panel::new();
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        assert!(texts.iter().any(|(t, _)| t == "Method:"), "{texts:?}");
-        let shown = texts.iter().find(|(t, _)| t == "Classic").expect("Classic shown").1;
-        let undo = app.session.doc().unwrap().history.undo.len();
-        let texts = p.click(&mut app, shown);
-        let option = texts.iter().find(|(t, _)| t == "Perceptual").expect("the menu lists Perceptual").1;
-        p.click(&mut app, option);
-        assert_eq!(fill(&app).gradient.method, GradientMethod::Perceptual);
-        assert_eq!(app.session.doc().unwrap().history.undo.len(), undo + 1, "one undo step");
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        assert!(texts.iter().any(|(t, _)| t == "Perceptual"), "the menu shows the method: {texts:?}");
-        app.run("edit.undo", json!({})).unwrap();
-        assert_eq!(fill(&app).gradient.method, GradientMethod::Classic);
-    }
-
-    #[test]
-    fn a_selected_diamond_shows_and_sets_its_midpoint_in_location() {
-        let stops = json!([{"offset": 0, "color": "#ffffff", "midpoint": 0.3}, {"offset": 1, "color": "#000000"}]);
-        let mut app = app(json!({"gradient": {"stops": stops}}));
-        app.run("gradient.selectStop", json!({"index": 1})).unwrap();
-        let mut p = Panel::new();
-        let texts = p.frame(&mut app, vec![], Modifiers::NONE);
-        assert!(texts.iter().any(|(t, _)| t == "100%"), "the stop's location: {texts:?}");
-        let diamond = p.widget(("grad-mid", 0));
-        let texts = p.click(&mut app, diamond.center());
-        assert_eq!(app.session.selected_stop(), None, "the diamond replaces the stop selection");
-        assert!(texts.iter().any(|(t, _)| t == "30%"), "the midpoint: {texts:?}");
-        // Typing a location moves the midpoint.
-        let field = texts.iter().find(|(t, _)| t == "30%").unwrap().1;
-        p.click(&mut app, field);
-        let key = |k, modifiers| Event::Key { key: k, physical_key: None, pressed: true, repeat: false, modifiers };
-        p.frame(&mut app, vec![key(egui::Key::A, Modifiers::COMMAND), Event::Text("60".into())], Modifiers::NONE);
-        p.frame(&mut app, vec![key(egui::Key::Enter, Modifiers::NONE)], Modifiers::NONE);
-        assert!((fill(&app).gradient.stops[0].midpoint - 0.6).abs() < 1e-6, "{:?}", fill(&app).gradient.stops);
-        // Clicking a stop selects it again.
-        let stop = p.widget(("grad-stop", 0));
-        let texts = p.click(&mut app, stop.center());
-        assert_eq!(app.session.selected_stop(), Some(0));
-        assert!(texts.iter().any(|(t, _)| t == "0%"));
-    }
-
-    #[test]
-    fn the_thumbnail_menu_applies_gradient_swatches_and_saves_one() {
-        let mut app = app(json!({"color": "#336699"}));
-        let stops = json!([{"offset": 0, "color": "#ff0000"}, {"offset": 1, "color": "#0000ff"}]);
-        app.run("swatch.new", json!({"name": "Dusk", "gradient": {"stops": stops}})).unwrap();
-        let mut p = Panel::new();
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        let menu = p.widget("grad-swatches").center();
-        let texts = p.click(&mut app, menu);
-        let dusk = texts.iter().find(|(t, _)| t == "Dusk").unwrap_or_else(|| panic!("the menu lists the swatch: {texts:?}")).1;
-        assert!(texts.iter().any(|(t, _)| t.ends_with("Save to Swatches")));
-        p.click(&mut app, dusk);
-        assert_eq!(hexes(&app), ["#ff0000", "#0000ff"]);
-        // Save to Swatches adds the current gradient.
-        let before = gradient_swatches(&app).len();
-        let texts = p.click(&mut app, menu);
-        let save = texts.iter().find(|(t, _)| t.ends_with("Save to Swatches")).unwrap().1;
-        p.click(&mut app, save);
-        assert_eq!(gradient_swatches(&app).len(), before + 1);
-    }
-
-    #[test]
-    fn alt_drag_copies_a_stop_and_alt_dropping_on_a_stop_swaps_colours() {
-        let mut app = app(json!({"gradient": {}}));
-        let mut p = Panel::new();
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        let (a, b) = (p.widget(("grad-stop", 0)).center(), p.widget(("grad-stop", 1)).center());
-        let mid = pos2((a.x + b.x) / 2.0, a.y);
-        let offsets = |app: &VectorcraftApp| fill(app).gradient.stops.iter().map(|s| (s.offset * 10.0).round() / 10.0).collect::<Vec<_>>();
-        // A plain drag moves the stop.
-        p.drag(&mut app, a, mid, Modifiers::NONE);
-        assert_eq!(offsets(&app), [0.5, 1.0]);
-        app.run("edit.undo", json!({})).unwrap();
-        // Alt leaves the original and drags a copy, selected on release; one undo step.
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        p.drag(&mut app, a, mid, Modifiers::ALT);
-        assert_eq!((offsets(&app), hexes(&app)), (vec![0.0, 0.5, 1.0], vec!["#ffffff".to_string(), "#ffffff".into(), "#000000".into()]));
-        assert_eq!(app.session.selected_stop(), Some(1));
-        // Alt-dropping the first stop on the last swaps their colours.
-        p.drag(&mut app, a, b, Modifiers::ALT);
-        assert_eq!((offsets(&app), hexes(&app)), (vec![0.0, 0.5, 1.0], vec!["#000000".to_string(), "#ffffff".into(), "#ffffff".into()]));
-        app.run("edit.undo", json!({})).unwrap();
-        app.run("edit.undo", json!({})).unwrap();
-        assert_eq!(hexes(&app), ["#ffffff", "#000000"]);
-    }
-
-    #[test]
-    fn a_dropped_swatch_adds_or_recolours_a_stop() {
-        let mut app = app(json!({"gradient": {}}));
-        let mut p = Panel::new();
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        let (a, b) = (p.widget(("grad-stop", 0)).center(), p.widget(("grad-stop", 1)).center());
-        let drop = |p: &mut Panel, app: &mut VectorcraftApp, at: Pos2| {
-            egui::DragAndDrop::set_payload(&p.ctx, PanelDrag::paint(Paint::solid(Color::rgb(1.0, 0.0, 0.0))));
-            p.frame(app, vec![Event::PointerMoved(at)], Modifiers::NONE);
-            let up = Event::PointerButton { pos: at, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE };
-            p.frame(app, vec![up], Modifiers::NONE);
-        };
-        drop(&mut p, &mut app, pos2((a.x + b.x) / 2.0, a.y - 20.0));
-        assert_eq!(hexes(&app), ["#ffffff", "#ff0000", "#000000"]);
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        let last = p.widget(("grad-stop", 2)).center();
-        drop(&mut p, &mut app, last);
-        assert_eq!(hexes(&app), ["#ffffff", "#ff0000", "#ff0000"]);
-        // A spot swatch tile dropped on a stop links it: editing the swatch recolours the stop.
-        app.run("swatch.new", json!({"name": "Ink", "color": "#cc0066", "spot": true})).unwrap();
-        let ink = app.session.doc().unwrap().doc.swatch("Ink").unwrap().paint.clone();
-        egui::DragAndDrop::set_payload(&p.ctx, PanelDrag::Paint { paint: ink, params: json!({"swatch": "Ink"}), rows: None, library: None });
-        p.frame(&mut app, vec![Event::PointerMoved(a)], Modifiers::NONE);
-        p.frame(
-            &mut app,
-            vec![Event::PointerButton { pos: a, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE }],
-            Modifiers::NONE,
-        );
-        let st = fill(&app).gradient.stops[0].clone();
-        assert_eq!((st.swatch.as_deref(), st.tint, st.color.to_hex()), (Some("Ink"), 1.0, "#cc0066".to_string()));
-        app.run("swatch.edit", json!({"name": "Ink", "color": "#0066cc"})).unwrap();
-        assert_eq!(hexes(&app)[0], "#0066cc");
-    }
-
-    /// In a CMYK document a color dropped on the ramp of an RGB gradient keeps its model, as the
-    /// gradient's other stops do.
-    #[test]
-    fn a_color_dropped_on_the_ramp_keeps_its_model_in_a_cmyk_document() {
-        let mut app = app(json!({"gradient": {}}));
-        app.run("file.documentColorMode", json!({"mode": "cmyk"})).unwrap();
-        let rgb = json!([{"offset": 0, "color": "#ffffff"}, {"offset": 1, "color": "#000000"}]);
-        app.run("paint.setFill", json!({"gradient": {"stops": rgb}, "keepModel": true})).unwrap();
-        let mut p = Panel::new();
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        let (a, b) = (p.widget(("grad-stop", 0)).center(), p.widget(("grad-stop", 1)).center());
-        let at = pos2((a.x + b.x) / 2.0, a.y - 20.0);
-        let red = Color::rgb(1.0, 0.0, 0.0);
-        egui::DragAndDrop::set_payload(&p.ctx, PanelDrag::paint(Paint::solid(red)));
-        p.frame(&mut app, vec![Event::PointerMoved(at)], Modifiers::NONE);
-        let up = Event::PointerButton { pos: at, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE };
-        p.frame(&mut app, vec![up], Modifiers::NONE);
-        let stops: Vec<Color> = fill(&app).gradient.stops.iter().map(|s| s.color).collect();
-        assert_eq!(stops, [Color::WHITE, red, Color::BLACK]);
-    }
-
-    #[test]
-    fn double_clicking_a_stop_opens_the_shared_popover_beside_it() {
-        let mut app = app(json!({"gradient": {}}));
-        let mut p = Panel::new();
-        p.frame(&mut app, vec![], Modifiers::NONE);
-        let stop = p.widget(("grad-stop", 1));
-        let b = |pressed| Event::PointerButton { pos: stop.center(), button: PointerButton::Primary, pressed, modifiers: Modifiers::NONE };
-        p.frame(&mut app, vec![Event::PointerMoved(stop.center()), b(true), b(false), b(true), b(false)], Modifiers::NONE);
-        let d = app.ui.dialog.clone().expect("the popover opened");
-        assert_eq!(
-            (d.kind.as_str(), &d.fields["index"], &d.fields["screen"]),
-            ("gradientStop", &json!(1), &json!([stop.left(), stop.bottom() + 4.0]))
-        );
-        assert_eq!(app.session.selected_stop(), Some(1));
-    }
-
-    #[test]
-    fn the_stop_eyedropper_arms_the_eyedropper_for_the_stop() {
-        let mut app = app(json!({"gradient": {}}));
-        app.select_tool("gradient");
-        app.run("gradient.selectStop", json!({"index": 0})).unwrap();
-        let texts = Panel::new().frame(&mut app, vec![], Modifiers::NONE);
-        assert!(texts.iter().any(|(t, _)| t == "#FFFFFF"), "the stop's colour row: {texts:?}");
-        stop_eyedropper(&mut app);
-        assert_eq!((app.session.tool_id(), app.session.tool_options()), ("eyedropper", json!({"stop": "gradient", "brushKeyColor": false})));
-    }
-
-    /// The gradient panel names its Angle and Aspect Ratio inputs.
-    #[test]
-    fn angle_and_aspect_fields_are_named() {
-        use egui_kittest::kittest::Queryable;
-        let app = app(json!({"gradient": {}}));
-        let mut fonts = false;
-        let mut h = egui_kittest::Harness::builder().with_size(egui::vec2(280.0, 640.0)).with_accessibility_check(false).build_ui_state(
-            move |ui, app: &mut VectorcraftApp| {
-                if !std::mem::replace(&mut fonts, true) {
-                    crate::theme::install_fonts(ui.ctx());
-                    return;
-                }
-                show(app, ui);
-            },
-            app,
-        );
-        h.run_steps(3);
-        let _ = h.get_by_role_and_label(egui::accesskit::Role::TextInput, "Angle");
-        let _ = h.get_by_role_and_label(egui::accesskit::Role::TextInput, "Aspect Ratio");
-    }
-}
+mod tests;
diff --git a/crates/ui-egui/src/panels/gradient/tests.rs b/crates/ui-egui/src/panels/gradient/tests.rs
new file mode 100644
index 000000000..a4dac7825
--- /dev/null
+++ b/crates/ui-egui/src/panels/gradient/tests.rs
@@ -0,0 +1,445 @@
+use egui::{Event, Modifiers, PointerButton};
+use vectorcraft_engine::Session;
+
+use super::*;
+
+#[test]
+fn offsets_and_json() {
+    assert_eq!(x_to_offset(50.0, 0.0, 200.0), 0.25);
+    assert_eq!(x_to_offset(-5.0, 0.0, 200.0), 0.0);
+    assert_eq!(x_to_offset(500.0, 0.0, 200.0), 1.0);
+    let j = stops_json(&Gradient::default().stops);
+    assert_eq!(j.as_array().unwrap().len(), 2);
+    assert_eq!(j[1]["midpoint"], json!(0.5));
+}
+
+#[test]
+fn dropped_colours_recolour_or_add_an_opaque_stop() {
+    let mut g = Gradient::default();
+    g.stops[1].opacity = 0.5;
+    let red = Color::rgb(1.0, 0.0, 0.0);
+    let (v, i) = drop_color(&g, Some(1), 0.3, red, None);
+    assert_eq!((v.len(), i, v[1].color, v[1].opacity), (2, 1, red, 1.0));
+    let (v, i) = drop_color(&g, None, 0.3, red, None);
+    assert_eq!((v.len(), i, v[1].color, v[1].offset, v[1].opacity), (3, 1, red, 0.3, 1.0));
+}
+
+/// In a CMYK document an RGB swatch's color applied to the selected stop or freeform point
+/// keeps its model, as the swatch applied to a fill does.
+#[test]
+fn a_swatch_color_on_a_stop_or_a_point_keeps_its_model_in_a_cmyk_document() {
+    let stops = json!([{"offset": 0, "color": {"c": 0, "m": 0, "y": 0, "k": 0}}, {"offset": 1, "color": {"c": 0, "m": 0, "y": 0, "k": 1}}]);
+    let mut app = app(json!({"gradient": {"stops": stops}}));
+    app.run("file.documentColorMode", json!({"mode": "cmyk"})).unwrap();
+    let orange = Color::rgb8(255, 128, 0);
+    app.run("swatch.new", json!({"name": "Screen", "color": "#ff8000", "keepModel": true})).unwrap();
+    app.run("gradient.selectStop", json!({"index": 1})).unwrap();
+    assert!(recolor_selected(&mut app, orange, &json!({"swatch": "Screen"})));
+    let Paint::Gradient(g) = active_paint(&app) else { panic!("a gradient fill") };
+    assert_eq!(g.gradient.stops[1].color, orange);
+    app.run("paint.editGradient", json!({"kind": "freeform"})).unwrap();
+    app.run("paint.freeform.selectPoint", json!({"index": 1})).unwrap();
+    assert!(recolor_selected(&mut app, orange, &json!({"swatch": "Screen"})));
+    let Paint::Gradient(g) = active_paint(&app) else { panic!("a gradient fill") };
+    assert_eq!(g.freeform.map(|f| f.points[1].color), Some(orange));
+}
+
+/// In a CMYK document Add to Swatches and Save to Swatches keep the gradient's RGB stops RGB.
+#[test]
+fn a_gradient_saved_as_a_swatch_keeps_its_stops_models_in_a_cmyk_document() {
+    let mut app = app(json!({"color": "#000000"}));
+    app.run("file.documentColorMode", json!({"mode": "cmyk"})).unwrap();
+    let stops = json!([{"offset": 0, "color": "#ff8000"}, {"offset": 1, "color": {"c": 0, "m": 0, "y": 0, "k": 1}}]);
+    app.run("paint.setFill", json!({"gradient": {"stops": stops}, "keepModel": true})).unwrap();
+    let g = current(&app).expect("a gradient fill");
+    let colors = |g: &GradientPaint| g.gradient.stops.iter().map(|s| s.color).collect::<Vec<_>>();
+    assert_eq!(colors(&g), [Color::rgb8(255, 128, 0), Color::cmyk(0.0, 0.0, 0.0, 1.0)]);
+    save_to_swatches(&mut app, &g);
+    let Some(Paint::Gradient(saved)) = app.session.doc().unwrap().doc.swatches.last().map(|w| w.paint.clone()) else {
+        panic!("a gradient swatch")
+    };
+    assert_eq!(colors(&saved), colors(&g));
+}
+
+#[test]
+fn dragged_stops_move_copy_or_swap() {
+    let g = Gradient::default();
+    let (v, i) = dragged_stops(&g.stops, 0, 0.4, false, Some(1));
+    assert_eq!((v.len(), i, v[0].offset), (2, 0, 0.4));
+    let (v, i) = dragged_stops(&g.stops, 0, 0.4, true, None);
+    assert_eq!((v.len(), i, v[1].offset, v[1].color), (3, 1, 0.4, Color::WHITE));
+    let (v, i) = dragged_stops(&g.stops, 0, 1.0, true, Some(1));
+    assert_eq!((v.len(), i, v[0].color, v[1].color), (2, 0, Color::BLACK, Color::WHITE));
+    // Dropped on itself: a copy.
+    assert_eq!(dragged_stops(&g.stops, 0, 0.0, true, Some(0)).0.len(), 3);
+}
+
+// ---------- headless frames ----------
+
+/// A selected rectangle filled with `fill` (`paint.setFill` params).
+fn app(fill: Value) -> VectorcraftApp {
+    let mut app = VectorcraftApp::new(Session::new(), Default::default());
+    app.run("file.new", json!({"width": 300, "height": 300})).unwrap();
+    app.run("shape.rectangle", json!({"x": 100, "y": 100, "width": 100, "height": 100})).unwrap();
+    app.run("paint.setFill", fill).unwrap();
+    app
+}
+
+/// A headless Gradient panel: frames share one context and a clock.
+struct Panel {
+    ctx: egui::Context,
+    time: f64,
+}
+
+impl Panel {
+    fn new() -> Self {
+        let ctx = egui::Context::default();
+        crate::theme::install_fonts(&ctx);
+        Self { ctx, time: 0.0 }
+    }
+
+    /// One frame with `events` (and `modifiers` held); returns the texts drawn and where.
+    fn frame(&mut self, app: &mut VectorcraftApp, events: Vec<Event>, modifiers: Modifiers) -> Vec<(String, Pos2)> {
+        fn texts(s: &egui::Shape, out: &mut Vec<(String, Pos2)>) {
+            match s {
+                egui::Shape::Text(t) => out.push((t.galley.text().to_string(), t.pos + t.galley.rect.center().to_vec2())),
+                egui::Shape::Vec(v) => v.iter().for_each(|s| texts(s, out)),
+                _ => {}
+            }
+        }
+        self.time += 0.1;
+        let mut events = events;
+        events.insert(0, Event::ModifiersChanged(modifiers));
+        let input = egui::RawInput {
+            time: Some(self.time),
+            events,
+            screen_rect: Some(Rect::from_min_size(Pos2::ZERO, vec2(260.0, 600.0))),
+            ..Default::default()
+        };
+        let mut out = self.ctx.run_ui(input, |ui| show(app, ui));
+        out.textures_delta.clear();
+        let mut v = vec![];
+        out.shapes.iter().for_each(|c| texts(&c.shape, &mut v));
+        v
+    }
+
+    /// The rect of the widget keyed `key` (last frame). egui 0.37's `WidgetRect.parent_id` is
+    /// the parent Ui's unstable `unique_id`, not the stable `scope_id` widgets are salted with;
+    /// debug builds remember the `with(key)` that made each id, so match that.
+    fn widget(&self, key: impl std::hash::Hash + std::fmt::Debug + Copy) -> Rect {
+        let suffix = format!(".with({key:?})");
+        self.ctx
+            .viewport(|vp| {
+                vp.prev_pass.widgets.layers().flat_map(|(_, w)| w.iter()).find(|w| format!("{:?}", w.id).ends_with(&suffix)).map(|w| w.rect)
+            })
+            .expect("widget drawn")
+    }
+
+    fn click(&mut self, app: &mut VectorcraftApp, at: Pos2) -> Vec<(String, Pos2)> {
+        let b = |pressed| Event::PointerButton { pos: at, button: PointerButton::Primary, pressed, modifiers: Modifiers::NONE };
+        self.frame(app, vec![Event::PointerMoved(at), b(true)], Modifiers::NONE);
+        self.frame(app, vec![b(false)], Modifiers::NONE);
+        self.frame(app, vec![], Modifiers::NONE)
+    }
+
+    /// The `size`-square widgets right of `at` on its row (last frame), left to right.
+    fn row_after(&self, at: Pos2, size: f32) -> Vec<Rect> {
+        let mut v: Vec<Rect> = self.ctx.viewport(|vp| {
+            vp.prev_pass
+                .widgets
+                .layers()
+                .flat_map(|(_, w)| w.iter())
+                .map(|w| w.rect)
+                .filter(|r| {
+                    (r.width() - size).abs() < 0.5 && (r.height() - size).abs() < 0.5 && (r.center().y - at.y).abs() < 8.0 && r.left() > at.x
+                })
+                .collect()
+        });
+        v.sort_by(|a, b| a.left().total_cmp(&b.left()));
+        v.dedup();
+        v
+    }
+
+    /// Press at `from`, move to `to` in steps and release there, with `m` held.
+    fn drag(&mut self, app: &mut VectorcraftApp, from: Pos2, to: Pos2, m: Modifiers) {
+        let b = |at, pressed| Event::PointerButton { pos: at, button: PointerButton::Primary, pressed, modifiers: m };
+        self.frame(app, vec![Event::PointerMoved(from), b(from, true)], m);
+        for k in 1..=4 {
+            self.frame(app, vec![Event::PointerMoved(from + (to - from) * (k as f32 / 4.0))], m);
+        }
+        self.frame(app, vec![b(to, false)], m);
+        self.frame(app, vec![], Modifiers::NONE);
+    }
+}
+
+fn fill(app: &VectorcraftApp) -> GradientPaint {
+    match crate::panels::current_paints(app).0 {
+        Paint::Gradient(g) => *g,
+        p => panic!("expected a gradient fill, got {p:?}"),
+    }
+}
+
+fn hexes(app: &VectorcraftApp) -> Vec<String> {
+    fill(app).gradient.stops.iter().map(|s| s.color.to_hex()).collect()
+}
+
+#[test]
+fn the_proxy_toggles_fill_and_stroke_and_stays_with_options_hidden() {
+    let mut app = app(json!({"gradient": {}}));
+    let mut p = Panel::new();
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    assert!(texts.iter().any(|(t, _)| t == "Opacity:"));
+    let stroke = p.widget("stroke-proxy");
+    p.click(&mut app, stroke.right_bottom() - vec2(2.0, 2.0));
+    assert!(!app.session.fill_active, "the Stroke proxy came to the front");
+    set_pstate(&p.ctx, HIDE_OPTIONS, true);
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    assert!(!texts.iter().any(|(t, _)| t == "Opacity:" || t == "Type:"), "{texts:?}");
+    let fill = p.widget("fill-proxy");
+    p.click(&mut app, fill.left_top() + vec2(2.0, 2.0));
+    assert!(app.session.fill_active, "the proxy works with the options hidden");
+    p.widget(("grad-stop", 1));
+}
+
+#[test]
+fn the_stroke_buttons_lay_the_gradient_within_along_or_across_the_stroke() {
+    let mut app = app(json!({"gradient": {}}));
+    app.run("paint.setStroke", json!({"gradient": {}, "focus": false})).unwrap();
+    assert!(app.session.fill_active);
+    let mode = |app: &VectorcraftApp| app.session.shown_stroke().unwrap().gradient_mode;
+    let mut p = Panel::new();
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    let label = texts.iter().find(|(t, _)| t == "Stroke:").expect("the Stroke buttons").1;
+    // With the Fill proxy in front they are off.
+    let buttons = p.row_after(label, 22.0);
+    assert_eq!(buttons.len(), 3);
+    p.click(&mut app, buttons[1].center());
+    assert_eq!(mode(&app), StrokeGradientMode::Within);
+    let stroke = p.widget("stroke-proxy");
+    p.click(&mut app, stroke.right_bottom() - vec2(2.0, 2.0));
+    assert!(!app.session.fill_active);
+    for (i, want) in [(1, StrokeGradientMode::Along), (2, StrokeGradientMode::Across), (0, StrokeGradientMode::Within)] {
+        p.click(&mut app, buttons[i].center());
+        assert_eq!(mode(&app), want);
+    }
+    app.run("edit.undo", json!({})).unwrap();
+    assert_eq!(mode(&app), StrokeGradientMode::Across, "one undo step per click");
+}
+
+#[test]
+fn the_dither_box_dithers_the_gradient_fill_and_is_off_for_strokes() {
+    let mut app = app(json!({"gradient": {}}));
+    app.run("paint.setStroke", json!({"gradient": {}, "focus": false})).unwrap();
+    let mut p = Panel::new();
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    let at = texts.iter().find(|(t, _)| t == "Dither").expect("the Dither box").1;
+    p.click(&mut app, at);
+    assert!(fill(&app).gradient.dither, "the fill's gradient is dithered");
+    p.click(&mut app, at);
+    assert!(!fill(&app).gradient.dither, "a second click clears it");
+    app.run("edit.undo", json!({})).unwrap();
+    assert!(fill(&app).gradient.dither, "one undo step per click");
+    // Behind the Stroke proxy the box is dimmed and does nothing.
+    let stroke = p.widget("stroke-proxy");
+    p.click(&mut app, stroke.right_bottom() - vec2(2.0, 2.0));
+    assert!(!app.session.fill_active);
+    let undo = app.session.doc().unwrap().history.undo.len();
+    p.click(&mut app, at);
+    assert_eq!(app.session.doc().unwrap().history.undo.len(), undo, "no edit on the stroke");
+    let Paint::Gradient(st) = app.session.shown_stroke().unwrap().paint.clone() else { panic!("a gradient stroke") };
+    assert!(!st.gradient.dither);
+}
+
+#[test]
+fn the_method_menu_makes_the_gradient_perceptual() {
+    let mut app = app(json!({"gradient": {}}));
+    let mut p = Panel::new();
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    assert!(texts.iter().any(|(t, _)| t == "Method:"), "{texts:?}");
+    let shown = texts.iter().find(|(t, _)| t == "Classic").expect("Classic shown").1;
+    let undo = app.session.doc().unwrap().history.undo.len();
+    let texts = p.click(&mut app, shown);
+    let option = texts.iter().find(|(t, _)| t == "Perceptual").expect("the menu lists Perceptual").1;
+    p.click(&mut app, option);
+    assert_eq!(fill(&app).gradient.method, GradientMethod::Perceptual);
+    assert_eq!(app.session.doc().unwrap().history.undo.len(), undo + 1, "one undo step");
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    assert!(texts.iter().any(|(t, _)| t == "Perceptual"), "the menu shows the method: {texts:?}");
+    app.run("edit.undo", json!({})).unwrap();
+    assert_eq!(fill(&app).gradient.method, GradientMethod::Classic);
+}
+
+#[test]
+fn a_selected_diamond_shows_and_sets_its_midpoint_in_location() {
+    let stops = json!([{"offset": 0, "color": "#ffffff", "midpoint": 0.3}, {"offset": 1, "color": "#000000"}]);
+    let mut app = app(json!({"gradient": {"stops": stops}}));
+    app.run("gradient.selectStop", json!({"index": 1})).unwrap();
+    let mut p = Panel::new();
+    let texts = p.frame(&mut app, vec![], Modifiers::NONE);
+    assert!(texts.iter().any(|(t, _)| t == "100%"), "the stop's location: {texts:?}");
+    let diamond = p.widget(("grad-mid", 0));
+    let texts = p.click(&mut app, diamond.center());
+    assert_eq!(app.session.selected_stop(), None, "the diamond replaces the stop selection");
+    assert!(texts.iter().any(|(t, _)| t == "30%"), "the midpoint: {texts:?}");
+    // Typing a location moves the midpoint.
+    let field = texts.iter().find(|(t, _)| t == "30%").unwrap().1;
+    p.click(&mut app, field);
+    let key = |k, modifiers| Event::Key { key: k, physical_key: None, pressed: true, repeat: false, modifiers };
+    p.frame(&mut app, vec![key(egui::Key::A, Modifiers::COMMAND), Event::Text("60".into())], Modifiers::NONE);
+    p.frame(&mut app, vec![key(egui::Key::Enter, Modifiers::NONE)], Modifiers::NONE);
+    assert!((fill(&app).gradient.stops[0].midpoint - 0.6).abs() < 1e-6, "{:?}", fill(&app).gradient.stops);
+    // Clicking a stop selects it again.
+    let stop = p.widget(("grad-stop", 0));
+    let texts = p.click(&mut app, stop.center());
+    assert_eq!(app.session.selected_stop(), Some(0));
+    assert!(texts.iter().any(|(t, _)| t == "0%"));
+}
+
+#[test]
+fn the_thumbnail_menu_applies_gradient_swatches_and_saves_one() {
+    let mut app = app(json!({"color": "#336699"}));
+    let stops = json!([{"offset": 0, "color": "#ff0000"}, {"offset": 1, "color": "#0000ff"}]);
+    app.run("swatch.new", json!({"name": "Dusk", "gradient": {"stops": stops}})).unwrap();
+    let mut p = Panel::new();
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    let menu = p.widget("grad-swatches").center();
+    let texts = p.click(&mut app, menu);
+    let dusk = texts.iter().find(|(t, _)| t == "Dusk").unwrap_or_else(|| panic!("the menu lists the swatch: {texts:?}")).1;
+    assert!(texts.iter().any(|(t, _)| t.ends_with("Save to Swatches")));
+    p.click(&mut app, dusk);
+    assert_eq!(hexes(&app), ["#ff0000", "#0000ff"]);
+    // Save to Swatches adds the current gradient.
+    let before = gradient_swatches(&app).len();
+    let texts = p.click(&mut app, menu);
+    let save = texts.iter().find(|(t, _)| t.ends_with("Save to Swatches")).unwrap().1;
+    p.click(&mut app, save);
+    assert_eq!(gradient_swatches(&app).len(), before + 1);
+}
+
+#[test]
+fn alt_drag_copies_a_stop_and_alt_dropping_on_a_stop_swaps_colours() {
+    let mut app = app(json!({"gradient": {}}));
+    let mut p = Panel::new();
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    let (a, b) = (p.widget(("grad-stop", 0)).center(), p.widget(("grad-stop", 1)).center());
+    let mid = pos2((a.x + b.x) / 2.0, a.y);
+    let offsets = |app: &VectorcraftApp| fill(app).gradient.stops.iter().map(|s| (s.offset * 10.0).round() / 10.0).collect::<Vec<_>>();
+    // A plain drag moves the stop.
+    p.drag(&mut app, a, mid, Modifiers::NONE);
+    assert_eq!(offsets(&app), [0.5, 1.0]);
+    app.run("edit.undo", json!({})).unwrap();
+    // Alt leaves the original and drags a copy, selected on release; one undo step.
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    p.drag(&mut app, a, mid, Modifiers::ALT);
+    assert_eq!((offsets(&app), hexes(&app)), (vec![0.0, 0.5, 1.0], vec!["#ffffff".to_string(), "#ffffff".into(), "#000000".into()]));
+    assert_eq!(app.session.selected_stop(), Some(1));
+    // Alt-dropping the first stop on the last swaps their colours.
+    p.drag(&mut app, a, b, Modifiers::ALT);
+    assert_eq!((offsets(&app), hexes(&app)), (vec![0.0, 0.5, 1.0], vec!["#000000".to_string(), "#ffffff".into(), "#ffffff".into()]));
+    app.run("edit.undo", json!({})).unwrap();
+    app.run("edit.undo", json!({})).unwrap();
+    assert_eq!(hexes(&app), ["#ffffff", "#000000"]);
+}
+
+#[test]
+fn a_dropped_swatch_adds_or_recolours_a_stop() {
+    let mut app = app(json!({"gradient": {}}));
+    let mut p = Panel::new();
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    let (a, b) = (p.widget(("grad-stop", 0)).center(), p.widget(("grad-stop", 1)).center());
+    let drop = |p: &mut Panel, app: &mut VectorcraftApp, at: Pos2| {
+        egui::DragAndDrop::set_payload(&p.ctx, PanelDrag::paint(Paint::solid(Color::rgb(1.0, 0.0, 0.0))));
+        p.frame(app, vec![Event::PointerMoved(at)], Modifiers::NONE);
+        let up = Event::PointerButton { pos: at, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE };
+        p.frame(app, vec![up], Modifiers::NONE);
+    };
+    drop(&mut p, &mut app, pos2((a.x + b.x) / 2.0, a.y - 20.0));
+    assert_eq!(hexes(&app), ["#ffffff", "#ff0000", "#000000"]);
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    let last = p.widget(("grad-stop", 2)).center();
+    drop(&mut p, &mut app, last);
+    assert_eq!(hexes(&app), ["#ffffff", "#ff0000", "#ff0000"]);
+    // A spot swatch tile dropped on a stop links it: editing the swatch recolours the stop.
+    app.run("swatch.new", json!({"name": "Ink", "color": "#cc0066", "spot": true})).unwrap();
+    let ink = app.session.doc().unwrap().doc.swatch("Ink").unwrap().paint.clone();
+    egui::DragAndDrop::set_payload(&p.ctx, PanelDrag::Paint { paint: ink, params: json!({"swatch": "Ink"}), rows: None, library: None });
+    p.frame(&mut app, vec![Event::PointerMoved(a)], Modifiers::NONE);
+    p.frame(
+        &mut app,
+        vec![Event::PointerButton { pos: a, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE }],
+        Modifiers::NONE,
+    );
+    let st = fill(&app).gradient.stops[0].clone();
+    assert_eq!((st.swatch.as_deref(), st.tint, st.color.to_hex()), (Some("Ink"), 1.0, "#cc0066".to_string()));
+    app.run("swatch.edit", json!({"name": "Ink", "color": "#0066cc"})).unwrap();
+    assert_eq!(hexes(&app)[0], "#0066cc");
+}
+
+/// In a CMYK document a color dropped on the ramp of an RGB gradient keeps its model, as the
+/// gradient's other stops do.
+#[test]
+fn a_color_dropped_on_the_ramp_keeps_its_model_in_a_cmyk_document() {
+    let mut app = app(json!({"gradient": {}}));
+    app.run("file.documentColorMode", json!({"mode": "cmyk"})).unwrap();
+    let rgb = json!([{"offset": 0, "color": "#ffffff"}, {"offset": 1, "color": "#000000"}]);
+    app.run("paint.setFill", json!({"gradient": {"stops": rgb}, "keepModel": true})).unwrap();
+    let mut p = Panel::new();
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    let (a, b) = (p.widget(("grad-stop", 0)).center(), p.widget(("grad-stop", 1)).center());
+    let at = pos2((a.x + b.x) / 2.0, a.y - 20.0);
+    let red = Color::rgb(1.0, 0.0, 0.0);
+    egui::DragAndDrop::set_payload(&p.ctx, PanelDrag::paint(Paint::solid(red)));
+    p.frame(&mut app, vec![Event::PointerMoved(at)], Modifiers::NONE);
+    let up = Event::PointerButton { pos: at, button: PointerButton::Primary, pressed: false, modifiers: Modifiers::NONE };
+    p.frame(&mut app, vec![up], Modifiers::NONE);
+    let stops: Vec<Color> = fill(&app).gradient.stops.iter().map(|s| s.color).collect();
+    assert_eq!(stops, [Color::WHITE, red, Color::BLACK]);
+}
+
+#[test]
+fn double_clicking_a_stop_opens_the_shared_popover_beside_it() {
+    let mut app = app(json!({"gradient": {}}));
+    let mut p = Panel::new();
+    p.frame(&mut app, vec![], Modifiers::NONE);
+    let stop = p.widget(("grad-stop", 1));
+    let b = |pressed| Event::PointerButton { pos: stop.center(), button: PointerButton::Primary, pressed, modifiers: Modifiers::NONE };
+    p.frame(&mut app, vec![Event::PointerMoved(stop.center()), b(true), b(false), b(true), b(false)], Modifiers::NONE);
+    let d = app.ui.dialog.clone().expect("the popover opened");
+    assert_eq!(
+        (d.kind.as_str(), &d.fields["index"], &d.fields["screen"]),
+        ("gradientStop", &json!(1), &json!([stop.left(), stop.bottom() + 4.0]))
+    );
+    assert_eq!(app.session.selected_stop(), Some(1));
+}
+
+#[test]
+fn the_stop_eyedropper_arms_the_eyedropper_for_the_stop() {
+    let mut app = app(json!({"gradient": {}}));
+    app.select_tool("gradient");
+    app.run("gradient.selectStop", json!({"index": 0})).unwrap();
+    let texts = Panel::new().frame(&mut app, vec![], Modifiers::NONE);
+    assert!(texts.iter().any(|(t, _)| t == "#FFFFFF"), "the stop's colour row: {texts:?}");
+    stop_eyedropper(&mut app);
+    assert_eq!((app.session.tool_id(), app.session.tool_options()), ("eyedropper", json!({"stop": "gradient", "brushKeyColor": false})));
+}
+
+/// The gradient panel names its Angle and Aspect Ratio inputs.
+#[test]
+fn angle_and_aspect_fields_are_named() {
+    use egui_kittest::kittest::Queryable;
+    let app = app(json!({"gradient": {}}));
+    let mut fonts = false;
+    let mut h = egui_kittest::Harness::builder().with_size(egui::vec2(280.0, 640.0)).with_accessibility_check(false).build_ui_state(
+        move |ui, app: &mut VectorcraftApp| {
+            if !std::mem::replace(&mut fonts, true) {
+                crate::theme::install_fonts(ui.ctx());
+                return;
+            }
+            show(app, ui);
+        },
+        app,
+    );
+    h.run_steps(3);
+    let _ = h.get_by_role_and_label(egui::accesskit::Role::TextInput, "Angle");
+    let _ = h.get_by_role_and_label(egui::accesskit::Role::TextInput, "Aspect Ratio");
+}