Add visual context on tree view

issue8562
review261951002

production.py

@@ -492,6 +492,12 @@ class Production(Workflow, ModelSQL, ModelView):
                     costs=self.cost,
                     outputs=cost_price))
 
+    @classmethod
+    def view_attributes(cls):
+        return [
+            ('/tree', 'visual', If(Eval('state') == 'cancel', 'muted', '')),
+            ]
+
     @classmethod
     def create(cls, vlist):
         Sequence = Pool().get('ir.sequence')