diff --git a/opportunity.py b/opportunity.py
index b46cb1de04..11913c15b2 100644
--- a/opportunity.py
+++ b/opportunity.py
@@ -253,7 +253,7 @@ class SaleOpportunity(
 
     @classmethod
     def view_attributes(cls):
-        return [
+        return super().view_attributes() + [
             ('/tree', 'visual', If(Eval('state') == 'cancelled', 'muted', '')),
             ]