fix filter by mark flag

python/graph_list_sort_filter_proxy_model.py

@@ -65,9 +65,9 @@ class GraphListSortFilterProxyModel(QSortFilterProxyModel):
 
         # hide_unmarked
         if self.hide_unmarked:
-            mark_index = super().sourceModel.index(
+            mark_index = super().sourceModel().index(
                                        row, MARK_COLUMN, source_parent)
-            if super().sourceModel.data(mark_index) != "M":
+            if super().sourceModel().data(mark_index) != "M":
                 return False
 
         # hide_unmatched_event_condition_traces