Fix missing string attribute

Author: AndrejaKovacic

Orange/widgets/visualize/owvenndiagram.py

@@ -214,6 +214,8 @@ def intersectionStringAttrs(self):
     def _setInterAttributes(self):
         model = self.controls.selected_feature.model()
         model[:] = [None] + list(self.intersectionStringAttrs())
+        #if self.selected_feature not in model:
+        #    self.selected_feature = model[0]
 
     def _itemsForInput(self, key):
         """