diff --git a/crates/ui-egui/src/colorpicker.rs b/crates/ui-egui/src/colorpicker.rs
index e55130c5..581c65a2 100644
--- a/crates/ui-egui/src/colorpicker.rs
+++ b/crates/ui-egui/src/colorpicker.rs
@@ -400,7 +400,15 @@ fn alpha_slider(ui: &mut Ui, rect: Rect, color: Color) -> Option<(f32, bool)> {
 
 pub fn show(app: &mut FigApp, ctx: &egui::Context) {
     let Some(target) = app.ui.picker.clone() else { return };
-    let Some(mut paint) = current_paint(app, &target) else {
+    // A layer's picker belongs to the selection it was opened for: once that changes, close it
+    // rather than keep editing layers that are no longer selected.
+    let stale = match &target {
+        PickerTarget::Paint { ids, .. } | PickerTarget::Effect { ids, .. } => *ids != app.session.selection(),
+        PickerTarget::TextRange { id, .. } => !app.session.selection().contains(id),
+        _ => false,
+    };
+    let current = if stale { None } else { current_paint(app, &target) };
+    let Some(mut paint) = current else {
         app.ui.picker = None;
         return;
     };
diff --git a/crates/ui-egui/src/colorpicker_selection_tests.rs b/crates/ui-egui/src/colorpicker_selection_tests.rs
new file mode 100644
index 00000000..57aae197
--- /dev/null
+++ b/crates/ui-egui/src/colorpicker_selection_tests.rs
@@ -0,0 +1,54 @@
+//! The colour picker of a layer's paint or effect closes when that layer is no longer the
+//! selection, so it never keeps editing a layer that was deselected (#396).
+
+use figcraft_doc::NodeId;
+use figcraft_engine::Session;
+use serde_json::json;
+
+use crate::colorpicker::PickerTarget;
+use crate::layers_drag_tests::Ui;
+
+fn rect(s: &mut Session, x: f64) -> NodeId {
+    let v = s.execute("shape.rectangle", &json!({"x": x, "y": 0, "width": 20, "height": 20})).unwrap();
+    NodeId(v["id"].as_u64().unwrap())
+}
+
+fn two() -> (Ui, NodeId, NodeId) {
+    let mut s = Session::new();
+    let a = rect(&mut s, 0.0);
+    let b = rect(&mut s, 40.0);
+    s.execute("select.set", &json!({"ids": [a]})).unwrap();
+    (Ui::new(s), a, b)
+}
+
+#[test]
+fn picker_closes_when_its_layer_is_deselected() {
+    for effect in [false, true] {
+        let (mut u, a, _) = two();
+        let target = if effect {
+            u.app.run("effect.add", json!({"ids": [a], "type": "dropShadow"}));
+            PickerTarget::Effect { ids: vec![a], index: 0, secondary: false }
+        } else {
+            PickerTarget::Paint { fills: true, index: 0, ids: vec![a] }
+        };
+        u.app.ui.picker = Some(target.clone());
+        u.frame(vec![]);
+        u.frame(vec![]);
+        assert_eq!(u.app.ui.picker, Some(target.clone()), "the picker opens while its layer is selected");
+        u.app.run("select.none", json!({}));
+        u.frame(vec![]);
+        u.frame(vec![]);
+        assert!(u.app.ui.picker.is_none(), "deselecting closes {target:?}");
+    }
+}
+
+#[test]
+fn picker_closes_when_another_layer_is_selected() {
+    let (mut u, a, b) = two();
+    u.app.ui.picker = Some(PickerTarget::Paint { fills: true, index: 0, ids: vec![a] });
+    u.frame(vec![]);
+    u.app.run("select.set", json!({"ids": [b]}));
+    u.frame(vec![]);
+    u.frame(vec![]);
+    assert!(u.app.ui.picker.is_none(), "selecting another layer closes the picker: {:?}", u.app.ui.picker);
+}
diff --git a/crates/ui-egui/src/lib.rs b/crates/ui-egui/src/lib.rs
index 9f166dfa..6e12762b 100644
--- a/crates/ui-egui/src/lib.rs
+++ b/crates/ui-egui/src/lib.rs
@@ -75,6 +75,8 @@ mod canvas_drag_tests;
 #[cfg(test)]
 mod canvas_fixes_tests;
 #[cfg(test)]
+mod colorpicker_selection_tests;
+#[cfg(test)]
 mod comments_tests;
 #[cfg(test)]
 mod cursors_tests;