diff --git a/crates/ui-egui/src/panel_remove_tests.rs b/crates/ui-egui/src/panel_remove_tests.rs
index ee289bb8..3805dca3 100644
--- a/crates/ui-egui/src/panel_remove_tests.rs
+++ b/crates/ui-egui/src/panel_remove_tests.rs
@@ -1,5 +1,6 @@
-//! Removing fill, effect and layout grid rows in the Design panel, driven through egui headless: an
-//! open colour picker and open settings stay with their items, and go when their item goes.
+//! Adding and removing fill, effect and layout grid rows in the Design panel, driven through egui headless:
+//! adding a paint opens its colour picker; an open colour picker and open settings stay with their items,
+//! and go when their item goes.
 
 use egui::{Event, Id, Pos2};
 use figcraft_doc::NodeId;
@@ -124,6 +125,14 @@ fn removing_effects_and_grids_keeps_open_settings_with_their_rows() {
     assert!(flag(&u, "grid_open", 0) && !flag(&u, "grid_open", 1));
 }
 
+/// The centre of the button labelled `label` (found in the AccessKit tree).
+fn button(u: &mut Ui, label: &str) -> Pos2 {
+    let out = u.frame_output(vec![]);
+    let b = out.platform_output.accesskit_update.unwrap().nodes.into_iter().find(|(_, n)| n.label() == Some(label)).and_then(|(_, n)| n.bounds());
+    let b = b.unwrap_or_else(|| panic!("no {label:?} button"));
+    Pos2::new(((b.x0 + b.x1) / 2.0) as f32, ((b.y0 + b.y1) / 2.0) as f32)
+}
+
 #[test]
 fn adding_a_fill_or_stroke_opens_the_color_picker() {
     let mut s = Session::new();
@@ -133,31 +142,28 @@ fn adding_a_fill_or_stroke_opens_the_color_picker() {
     u.ctx.enable_accesskit();
     assert_eq!(u.app.ui.picker, None);
 
-    let out = u.frame_output(vec![]);
-    let add_fill = out
-        .platform_output
-        .accesskit_update
-        .unwrap()
-        .nodes
-        .into_iter()
-        .find(|(_, n)| n.label() == Some("Add fill"))
-        .and_then(|(_, n)| n.bounds())
-        .map(|b| Pos2::new(((b.x0 + b.x1) / 2.0) as f32, ((b.y0 + b.y1) / 2.0) as f32))
-        .expect("Add fill button");
+    let add_fill = button(&mut u, "Add fill");
     click(&mut u, add_fill);
     assert_eq!(u.app.ui.picker, Some(PickerTarget::Paint { fills: true, index: 1, ids: vec![r] }));
 
-    let out = u.frame_output(vec![]);
-    let add_stroke = out
-        .platform_output
-        .accesskit_update
-        .unwrap()
-        .nodes
-        .into_iter()
-        .find(|(_, n)| n.label() == Some("Add stroke"))
-        .and_then(|(_, n)| n.bounds())
-        .map(|b| Pos2::new(((b.x0 + b.x1) / 2.0) as f32, ((b.y0 + b.y1) / 2.0) as f32))
-        .expect("Add stroke button");
+    let add_stroke = button(&mut u, "Add stroke");
     click(&mut u, add_stroke);
     assert_eq!(u.app.ui.picker, Some(PickerTarget::Paint { fills: false, index: 0, ids: vec![r] }));
 }
+
+#[test]
+fn adding_a_fill_to_mixed_fills_opens_no_picker() {
+    let mut s = Session::new();
+    let a = id(s.execute("shape.rectangle", &json!({"x": 0, "y": 0, "width": 50, "height": 50})).unwrap());
+    let b = id(s.execute("shape.rectangle", &json!({"x": 60, "y": 0, "width": 50, "height": 50})).unwrap());
+    s.execute("fill.add", &json!({"ids": [b]})).unwrap();
+    s.execute("select.set", &json!({"ids": [a, b]})).unwrap();
+    let mut u = Ui::new(s);
+    u.ctx.enable_accesskit();
+
+    let add_fill = button(&mut u, "Add fill");
+    click(&mut u, add_fill);
+    let doc = u.app.session.doc().unwrap();
+    assert_eq!((doc.node(a).unwrap().fills.len(), doc.node(b).unwrap().fills.len()), (2, 3));
+    assert_eq!(u.app.ui.picker, None);
+}
diff --git a/crates/ui-egui/src/right.rs b/crates/ui-egui/src/right.rs
index 5899a949..fcb13724 100644
--- a/crates/ui-egui/src/right.rs
+++ b/crates/ui-egui/src/right.rs
@@ -1101,13 +1101,11 @@ fn paints(app: &mut FigApp, ui: &mut Ui, doc: &Document, sel: &[NodeId], fills:
         empty,
     ) {
         if i == 1 {
-            if app.run(if fills { "fill.add" } else { "stroke.add" }, json!({"ids": ids})).is_some() {
-                if let Ok(doc) = app.session.doc() {
-                    let count = ids.first().and_then(|id| doc.node(*id)).map_or(0, |n| if fills { n.fills.len() } else { n.strokes.len() });
-                    if count > 0 {
-                        app.ui.picker = Some(crate::colorpicker::PickerTarget::Paint { fills, index: count - 1, ids: ids.clone() });
-                    }
-                }
+            // The new paint goes on top; open its picker. A mixed selection has no one index to edit.
+            if app.run(if fills { "fill.add" } else { "stroke.add" }, json!({"ids": ids})).is_some()
+                && let Some(l) = &list
+            {
+                app.ui.picker = Some(crate::colorpicker::PickerTarget::Paint { fills, index: l.len(), ids: ids.clone() });
             }
         } else {
             style_picker::open(app, ui, &ids, slot);