code: def opened_files_list_changed(self):
          
          # Refresh Python file dependent actions:
          editor = self.get_current_editor()
          if editor:
              python_enable = editor.is_python()
              cython_enable = python_enable or (
                  programs.is_module_installed('Cython') and editor.is_cython())
              for action in self.pythonfile_dependent_actions:
                  if action in self.cythonfile_compatible_actions:
                      enable = cython_enable
                  else:
                      enable = python_enable
                  if action is self.winpdb_action:
                      action.setEnabled(enable and WINPDB_PATH is not None)
                  else:
                      action.setEnabled(enable)
              self.open_file_update.emit(self.get_current_filename())
docs: Opened files list has changed:
          --> open/close file action
          --> modification ('*' added to title)
          --> current edited file has changed