diff --git a/crates/engine/src/cmd/appearance.rs b/crates/engine/src/cmd/appearance.rs
index 9bfddc7a..d4863d37 100644
--- a/crates/engine/src/cmd/appearance.rs
+++ b/crates/engine/src/cmd/appearance.rs
@@ -22,8 +22,8 @@ pub fn specs() -> Vec<CommandSpec> {
             "Appearance Item",
             [],
             None,
-            "{index, ids?, opacity?: 0..100, blend?, visible?, weight?, color?|none?|swatch?|gradient?} edit one fill/stroke of the appearance stack of the selection (or `ids`)",
-            has_selection,
+            "{index, ids?, opacity?: 0..100, blend?, visible?, weight?, color?|none?|swatch?|gradient?} edit one fill/stroke of the appearance stack of `ids` (default: the selection)",
+            has_doc,
             set_item
         ),
         cmd!("appearance.removeItem", "Remove Item", [], None, "{index}", has_selection, remove_item),
@@ -98,6 +98,9 @@ fn set_item(s: &mut Session, p: &Value) -> Result<Value> {
     let idx = p.get("index").and_then(Value::as_u64).ok_or_else(|| bad("appearance.setItem", "missing index"))? as usize;
     let paint = paint_from(s, p)?;
     let ids = paint_targets(s, p)?;
+    if ids.is_empty() {
+        return Err(bad("appearance.setItem", "select objects or give ids"));
+    }
     let blend = str_param(p, "blend").and_then(BlendMode::parse);
     s.edit("Appearance", |d, _| {
         for id in &ids {
diff --git a/crates/engine/src/tests_opacitymask.rs b/crates/engine/src/tests_opacitymask.rs
index b45b5355..b2c5b661 100644
--- a/crates/engine/src/tests_opacitymask.rs
+++ b/crates/engine/src/tests_opacitymask.rs
@@ -165,6 +165,11 @@ fn opacity_is_a_percentage_everywhere() {
     assert_eq!(doc(&s).node(a).unwrap().opacity, 1.0);
     s.execute("transparency.set", &json!({"opacity": 0.5})).unwrap();
     assert!((doc(&s).node(a).unwrap().opacity - 0.005).abs() < 1e-6);
+    // Appearance items take ids without a selection too.
+    s.execute("select.none", &json!({})).unwrap();
+    assert!(s.execute("appearance.setItem", &json!({"index": 0, "opacity": 30})).is_err(), "no selection, no ids");
+    s.execute("appearance.setItem", &json!({"index": 0, "ids": [a.0], "opacity": 30})).unwrap();
+    assert!((fill_opacity(&s) - 0.3).abs() < 1e-6);
 }
 
 #[test]
@@ -229,3 +234,35 @@ fn exports_while_editing_leave_the_editing_layer_out() {
     assert_eq!(pdf(&mut s).len(), pdf_editing.len());
     assert_eq!(png(&mut s), png_editing);
 }
+
+#[test]
+fn undo_and_redo_walk_in_and_out_of_mask_editing() {
+    let mut s = session();
+    let obj = rect(&mut s, 0.0, 200.0);
+    s.execute("transparency.makeOpacityMask", &json!({})).unwrap();
+    let layer = doc(&s).mask_edit.unwrap().layer;
+    s.execute("shape.rectangle", &json!({"x": 0, "y": 0, "width": 100, "height": 200})).unwrap();
+    s.execute("transparency.stopEditingOpacityMask", &json!({})).unwrap();
+    let state = |s: &Session| {
+        let st = s.doc().unwrap();
+        (st.doc.mask_edit.map(|m| m.layer), st.isolation, st.active_layer == Some(layer), has_edit_layer(&st.doc))
+    };
+    let editing = (Some(layer), Some(layer), true, true);
+    assert_eq!(state(&s), (None, None, false, false));
+    // Back into editing with the drawn art, then before it, then before the mask.
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(state(&s), editing);
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(state(&s), editing);
+    assert!(doc(&s).node(layer).unwrap().children().unwrap().is_empty());
+    s.execute("edit.undo", &json!({})).unwrap();
+    assert_eq!(state(&s), (None, None, false, false));
+    assert!(mask(&s, obj).is_none());
+    // And forward again.
+    s.execute("edit.redo", &json!({})).unwrap();
+    s.execute("edit.redo", &json!({})).unwrap();
+    assert_eq!(state(&s), editing);
+    s.execute("edit.redo", &json!({})).unwrap();
+    assert_eq!(state(&s), (None, None, false, false));
+    assert_eq!(mask(&s, obj).unwrap().art.geometric_bounds().unwrap().x1, 100.0);
+}