diff --git a/crates/ui-egui/src/prepare.rs b/crates/ui-egui/src/prepare.rs
index 07597c87a3..75ad8972ff 100644
--- a/crates/ui-egui/src/prepare.rs
+++ b/crates/ui-egui/src/prepare.rs
@@ -997,16 +997,20 @@ pub(crate) fn body(ui: &mut egui::Ui, d: &mut FieldDraft, t: &crate::theme::Toke
                 if let Some(l) = d.look.as_mut() {
                     widgets::section_title(ui, tl!("Borders and Colors"));
                     egui::Grid::new("field-borders").num_columns(2).spacing([12.0, 8.0]).show(ui, |ui| {
-                        for (label, slot) in [(tl!("Border Color:"), &mut l.border), (tl!("Fill Color:"), &mut l.fill)] {
+                        for (index, (label, slot)) in
+                            [(tl!("Border Color:"), &mut l.border), (tl!("Fill Color:"), &mut l.fill)].into_iter().enumerate()
+                        {
                             ui.label(label);
-                            ui.horizontal(|ui| {
-                                let mut none = slot.is_none();
-                                if ui.checkbox(&mut none, tl!("No color")).changed() {
-                                    *slot = if none { None } else { Some([0.0; 3]) };
-                                }
-                                if let Some(c) = crate::comments::swatch_grid(ui, *slot) {
-                                    *slot = Some(c);
-                                }
+                            ui.push_id(("field-color", index), |ui| {
+                                ui.horizontal(|ui| {
+                                    let mut none = slot.is_none();
+                                    if ui.checkbox(&mut none, tl!("No color")).changed() {
+                                        *slot = if none { None } else { Some([0.0; 3]) };
+                                    }
+                                    if let Some(c) = crate::comments::swatch_grid(ui, *slot) {
+                                        *slot = Some(c);
+                                    }
+                                });
                             });
                             ui.end_row();
                         }
diff --git a/crates/ui-egui/tests/prepare.rs b/crates/ui-egui/tests/prepare.rs
index cd6e013244..b23f1a9f8f 100644
--- a/crates/ui-egui/tests/prepare.rs
+++ b/crates/ui-egui/tests/prepare.rs
@@ -7,7 +7,8 @@ use egui_kittest::kittest::Queryable;
 use pdfcraft_ui_egui::{PdfCraftApp, QuickTool};
 
 fn harness() -> Harness<'static, PdfCraftApp> {
-    let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(|_cc| {
+    let mut h = Harness::builder().with_size(egui::vec2(1400.0, 900.0)).build_eframe(|cc| {
+        cc.egui_ctx.options_mut(|options| options.warn_on_id_clash = true);
         let mut app = PdfCraftApp::new();
         app.set_option("language", "en").unwrap();
         app.open_bytes("form.pdf", None, include_bytes!("data/form.pdf").to_vec()).unwrap();
@@ -157,6 +158,27 @@ fn appearance_tab_restyles_the_field() {
     h.get_by_label("Appearance").click();
     h.run_steps(2);
     h.get_by_label("Line Style:");
+    fn no_grid_id_warning(shape: &egui::Shape) -> bool {
+        match shape {
+            egui::Shape::Vec(shapes) => shapes.iter().all(no_grid_id_warning),
+            egui::Shape::Text(text) => !text.galley.job.text.contains("Grid ID"),
+            _ => true,
+        }
+    }
+    // Check egui's actual painted diagnostics, rather than reproducing the ID formula.
+    assert!(h.output().shapes.iter().all(|shape| no_grid_id_warning(&shape.shape)), "palette grids must not share an ID");
+    let before = h.state().field_props.as_ref().unwrap().look.unwrap();
+    assert_eq!(h.get_all_by_label("No color").count(), 2);
+    h.get_all_by_label("No color").next().unwrap().click();
+    h.run_steps(2);
+    let border = h.state().field_props.as_ref().unwrap().look.as_ref().unwrap().border;
+    assert_eq!(border, if before.border.is_some() { None } else { Some([0.0; 3]) });
+    assert_eq!(h.state().field_props.as_ref().unwrap().look.as_ref().unwrap().fill, before.fill);
+    h.get_all_by_label("No color").nth(1).unwrap().click();
+    h.run_steps(2);
+    let look = h.state().field_props.as_ref().unwrap().look.as_ref().unwrap();
+    assert_eq!(look.border, border);
+    assert_eq!(look.fill, if before.fill.is_some() { None } else { Some([0.0; 3]) });
     {
         let d = h.state_mut().field_props.as_mut().unwrap();
         let l = d.look.as_mut().expect("a look");