diff --git a/crates/ui-egui/src/panels/essential.rs b/crates/ui-egui/src/panels/essential.rs
index 26d458d4..2496b238 100644
--- a/crates/ui-egui/src/panels/essential.rs
+++ b/crates/ui-egui/src/panels/essential.rs
@@ -375,6 +375,37 @@ fn value_widget(app: &mut EffectcraftApp, ui: &mut egui::Ui, auto: &str, ty: Opt
             });
             r.response.rect
         }
+        // Scale keeps its Constrain Proportions link, on by default, as in After Effects (#338).
+        // The link is the property's own, shared with the Timeline's chain link.
+        ControlType::Point if p.match_id == "scale" && matches!(p.ui, ParamUi::Percent) => {
+            let comps = v.components();
+            let linked = !app.ui.timeline.unlinked.contains(&p.uid);
+            let (lr, link) = ui.allocate_exact_size(egui::vec2(14.0, 14.0), egui::Sense::click());
+            let t = app.tokens;
+            crate::icons::paint(ui.painter(), lr, crate::icons::Icon::Link, if linked { t.accent } else { t.text_faint });
+            let link = link.on_hover_text(tr("Constrain Proportions"));
+            app.auto.add(&format!("{auto}.link"), lr, "Constrain Proportions");
+            if link.clicked() && !app.ui.timeline.unlinked.remove(&p.uid) {
+                app.ui.timeline.unlinked.insert(p.uid);
+            }
+            let mut rect = lr;
+            for (d, &old) in comps.iter().enumerate() {
+                let mut x = old;
+                let r = ui.add(egui::DragValue::new(&mut x).speed(0.5).suffix(if d + 1 == comps.len() { "%" } else { "" }).max_decimals(1));
+                app.auto.add(&format!("{auto}.{d}"), r.rect, &p.name);
+                rect = rect.union(r.rect);
+                if r.changed() {
+                    // Alt edits one value of a linked pair, as in the Timeline.
+                    let next = if linked && !ui.input(|i| i.modifiers.alt) {
+                        widgets::constrained(&comps, d, x)
+                    } else {
+                        comps.iter().enumerate().map(|(e, &c)| if e == d { x } else { c }).collect()
+                    };
+                    out = Some(json!(next));
+                }
+            }
+            rect
+        }
         ControlType::Point => {
             let mut a = v.as_vec2();
             let r1 = ui.add(egui::DragValue::new(&mut a[0]).speed(1.0).max_decimals(1));
diff --git a/crates/ui-egui/src/panels/timeline.rs b/crates/ui-egui/src/panels/timeline.rs
index 7df3439b..15149560 100644
--- a/crates/ui-egui/src/panels/timeline.rs
+++ b/crates/ui-egui/src/panels/timeline.rs
@@ -3440,26 +3440,6 @@ fn fmt_num(v: f64, d: usize) -> String {
     format!("{v:.d$}")
 }
 
-/// Linked values after component `d` of `c` became `v`: the others scale by the same ratio
-/// (Constrain Proportions); from 0 the others that are 0 too follow the value.
-fn constrained(c: &[f64], d: usize, v: f64) -> Vec<f64> {
-    let Some(&old) = c.get(d) else { return c.to_vec() };
-    c.iter()
-        .enumerate()
-        .map(|(e, &x)| {
-            if e == d {
-                v
-            } else if old.abs() > 1e-9 {
-                x * v / old
-            } else if x.abs() <= 1e-9 {
-                v
-            } else {
-                x
-            }
-        })
-        .collect()
-}
-
 /// Inline value editor for a property row; pushes `prop.set` actions. Returns the rects of a
 /// multi-dimension value's fields, one per dimension (none for other values).
 fn value_editor(
@@ -3535,7 +3515,7 @@ fn value_editor(
                     // Alt edits one value of a linked pair.
                     let shown = if linked && !ui.input(|i| i.modifiers.alt) { n.min(c.len()) } else { 1 };
                     let from = if shown == 1 { d } else { 0 };
-                    for (e, v) in constrained(c.get(from..from + shown).unwrap_or_default(), d - from, nv).into_iter().enumerate() {
+                    for (e, v) in widgets::constrained(c.get(from..from + shown).unwrap_or_default(), d - from, nv).into_iter().enumerate() {
                         if let Some(slot) = nc.get_mut(from + e) {
                             *slot = v;
                         }
diff --git a/crates/ui-egui/src/widgets.rs b/crates/ui-egui/src/widgets.rs
index 8f12e52b..fdb8287b 100644
--- a/crates/ui-egui/src/widgets.rs
+++ b/crates/ui-egui/src/widgets.rs
@@ -559,3 +559,23 @@ pub fn popup_is_open(ui: &Ui, id: egui::Id) -> bool {
 pub fn open_popup(ui: &Ui, id: egui::Id) {
     ui.data_mut(|d| d.insert_temp(id.with("open"), true));
 }
+
+/// Linked values after component `d` of `c` became `v`: the others scale by the same ratio
+/// (Constrain Proportions); from 0 the others that are 0 too follow the value.
+pub(crate) fn constrained(c: &[f64], d: usize, v: f64) -> Vec<f64> {
+    let Some(&old) = c.get(d) else { return c.to_vec() };
+    c.iter()
+        .enumerate()
+        .map(|(e, &x)| {
+            if e == d {
+                v
+            } else if old.abs() > 1e-9 {
+                x * v / old
+            } else if x.abs() <= 1e-9 {
+                v
+            } else {
+                x
+            }
+        })
+        .collect()
+}
diff --git a/crates/ui-egui/tests/ui_panels.rs b/crates/ui-egui/tests/ui_panels.rs
index d58c2146..0ecefa48 100644
--- a/crates/ui-egui/tests/ui_panels.rs
+++ b/crates/ui-egui/tests/ui_panels.rs
@@ -271,3 +271,47 @@ fn panels_snapshot() {
         img.save(format!("{dir}/{panel}{scope}.png")).unwrap();
     }
 }
+
+/// Drag the automation element `id` horizontally by `dx` points.
+fn drag_x(h: &mut Harness<'_, EffectcraftApp>, id: &str, dx: f32) {
+    let e = h.state().auto.find(id).unwrap_or_else(|| panic!("no {id}")).clone();
+    let from: Pos2 = pos2(e.rect[0] + e.rect[2] / 2.0, e.rect[1] + e.rect[3] / 2.0);
+    h.input_mut().events.push(Event::PointerMoved(from));
+    h.step();
+    h.input_mut().events.push(Event::PointerButton { pos: from, button: egui::PointerButton::Primary, pressed: true, modifiers: Default::default() });
+    h.step();
+    for k in 1..=10 {
+        h.input_mut().events.push(Event::PointerMoved(from + egui::vec2(dx * k as f32 / 10.0, 0.0)));
+        h.step();
+    }
+    let to = from + egui::vec2(dx, 0.0);
+    h.input_mut().events.push(Event::PointerButton { pos: to, button: egui::PointerButton::Primary, pressed: false, modifiers: Default::default() });
+    h.run_steps(3);
+}
+
+/// #338: an Essential Graphics Scale control keeps After Effects' Constrain Proportions link, on
+/// by default: dragging X scales Y with it; unlinked, X moves alone.
+#[test]
+fn essential_graphics_scale_keeps_constrain_proportions() {
+    let mut h = harness();
+    let layer = h.state().session.active_comp().unwrap().layers[0].id.0;
+    h.state_mut().session.execute("prop.set", json!({"layer": layer, "path": "transform/scale", "value": [100.0, 50.0]})).unwrap();
+    let c =
+        h.state_mut().session.execute("essential.addProperty", json!({"layer": layer, "path": "transform/scale"})).unwrap()["controls"][0].as_u64().unwrap();
+    open(&mut h, "essentialGraphics");
+    let value = format!("essential.control.{c}.value");
+    let scale = |h: &Harness<'_, EffectcraftApp>| {
+        let comp = h.state().session.active_comp().unwrap();
+        let l = comp.layers.iter().find(|l| l.id.0 == layer).unwrap();
+        l.props.prop("transform/scale").unwrap().value.components()
+    };
+    assert!(h.state().auto.find(&format!("{value}.link")).is_some(), "the chain link is drawn");
+    drag_x(&mut h, &format!("{value}.0"), 40.0);
+    let linked = scale(&h);
+    assert!(linked[0] > 100.0, "{linked:?}");
+    assert!((linked[1] / linked[0] - 0.5).abs() < 1e-6, "Y follows X in proportion: {linked:?}");
+    click(&mut h, &format!("{value}.link"));
+    drag_x(&mut h, &format!("{value}.0"), 40.0);
+    let unlinked = scale(&h);
+    assert!(unlinked[0] > linked[0] && unlinked[1] == linked[1], "unlinked, X moves alone: {unlinked:?}");
+}