Update class_file_manager.py

Adapt to new /models

Author: woshimajintao

annotation_tool/controllers/classification/class_file_manager.py

@@ -76,6 +76,8 @@ def load_project(self, data, file_path):
 
         self.model.current_json_path = file_path
         self.model.json_loaded = True
+        
+        # [MV Note] populate_action_tree now uses self.main.tree_model internally
         self.main.populate_action_tree()
         self.main.update_save_export_button_state()
 
@@ -195,10 +197,13 @@ def create_new_project(self):
             self.ui.show_classification_view()
 
     def _clear_workspace(self, full_reset=False):
-        self.ui.classification_ui.left_panel.tree.clear()
+        # [MV Fix] Clear the Model, not the View
+        # self.ui.classification_ui.left_panel.tree.clear() # Old QTreeWidget code
+        self.main.tree_model.clear()
+        
         self.model.reset(full_reset)
         self.main.update_save_export_button_state()
         self.ui.classification_ui.right_panel.manual_box.setEnabled(False)
         self.ui.classification_ui.center_panel.show_single_view(None)
         if full_reset: 
-            self.main.setup_dynamic_ui()
+            self.main.setup_dynamic_ui()