EvaluationResultsContextHandler: Store class lists as tuples

Author: janezd

Orange/widgets/evaluate/contexthandlers.py

@@ -11,6 +11,9 @@ def open_context(self, widget, classes, classifier_names):
                 classes = classes.values
             else:
                 classes = None
+        if classes is not None:
+            # TODO: Remove this and similar casts when TupleList is eliminated
+            classes = tuple(classes)
         super().open_context(widget, classes, classifier_names)
 
     def new_context(self, classes, classifier_names):