Fix dialog header chevrons to collapse and restore forms

ROADMAP.md

@@ -292,6 +292,9 @@ headline counts in-scope tabs only and lists the deferred ones separately.
   continuous collision detection; local thin walls and small details remain limitations.
   See [contact-set limits and recovery](docs/contact-sets.md).
 
+Feature dialog header chevrons collapse and restore the form without discarding selections
+or edited values, including the Appearance panel.
+
 ## Document-opening performance
 
 - Cold rebuild profiling separates parsing, geometry, placement, display meshing and

crates/ui-egui/src/dialogs.rs

@@ -1326,7 +1326,17 @@ pub fn show(app: &mut SolveApp, ctx: &egui::Context) {
                 d.collapsed = !d.collapsed;
             }
             ui.label(RichText::new(heading.as_str()).strong().size(12.5));
-            crate::frame::right_aligned(ui, total, 8.0, |ui| ui.label(RichText::new("»").color(t.text_dim)));
+            let chevron_width = ui.spacing().interact_size.x;
+            crate::frame::right_aligned(ui, total, chevron_width, |ui| {
+                let chevron = if d.collapsed { "«" } else { "»" };
+                if ui
+                    .add(egui::Button::new(RichText::new(chevron).color(t.text_dim)).frame(false).min_size(vec2(chevron_width, 0.0)))
+                    .on_hover_text(if d.collapsed { "Expand" } else { "Collapse" })
+                    .clicked()
+                {
+                    d.collapsed = !d.collapsed;
+                }
+            });
         });
         if d.collapsed {
             return;

crates/ui-egui/src/dialogs_appearance.rs

@@ -594,6 +594,27 @@ mod tests {
         assert_eq!(a.session.doc.appearances.bodies.get("Body1"), a.session.doc.appearances.bodies.get("Body2"));
     }
 
+    #[test]
+    fn header_chevron_folds_and_restores_appearance_inputs() {
+        let mut h = crate::scenario::Harness::new();
+        h.app.run("solid.box", json!({"length":10,"width":10,"height":10})).unwrap();
+        h.app.session.selection = vec![Sel::Body { name: "Body1".into() }];
+        h.app.start("appearance.assign");
+        h.frames(3);
+        let before = h.app.dialog.clone().unwrap();
+        h.step(&json!({"widget":"»"})).unwrap();
+        assert!(h.app.dialog.as_ref().unwrap().collapsed);
+        assert!(h.widget("Appearance name").is_none());
+        h.step(&json!({"widget":"«"})).unwrap();
+        let after = h.app.dialog.as_ref().unwrap();
+        assert!(!after.collapsed);
+        assert_eq!(format!("{:?}", after.inputs), format!("{:?}", before.inputs));
+        let (Kind::Appearance(before), Kind::Appearance(after)) = (&before.kind, &after.kind) else { panic!("appearance dialog") };
+        assert_eq!(before.color, after.color);
+        assert_eq!(before.opacity, after.opacity);
+        assert_eq!(before.search, after.search);
+    }
+
     #[test]
     fn real_frames_and_unchanged_apply_keep_precise_opacity() {
         let mut h = crate::scenario::Harness::new();