Global Edit: the menu checks a selected group's kind only; its contents are checked on start

crates/engine/src/cmd/globaledit.rs

@@ -357,7 +357,10 @@ fn can_toggle(s: &Session) -> std::result::Result<(), String> {
     let [id] = st.selection.objects.as_slice() else {
         return Err(if st.selection.is_empty() { "nothing selected" } else { "select one object" }.into());
     };
+    // A group's contents are checked when Global Edit starts: building its shape here would walk
+    // every object in it each time the menu or the Properties panel asks.
     match st.doc.node(*id) {
+        Some(n) if n.extras().mask.is_none() && plain_group(n) => Ok(()),
         Some(n) if supported(n) => Ok(()),
         _ => Err(UNSUPPORTED.into()),
     }

crates/engine/src/tests/globaledit.rs

@@ -295,8 +295,10 @@ fn global_edit_needs_one_supported_object() {
     };
     let (g, _) = (group(&mut s, 600.0), group(&mut s, 700.0));
     sel(&mut s, &[g]);
+    // The menu only checks that it is a group; starting refuses its contents.
     let e = s.execute("select.globalEdit", &json!({})).unwrap_err();
-    assert!(matches!(e, EngineError::Disabled(..)) && e.to_string().contains("symbol instances and groups of them"), "{e}");
+    assert!(e.to_string().contains("symbol instances and groups of them"), "{e}");
+    assert!(s.doc().unwrap().global_edit.is_none());
 }
 
 #[test]