code: def updateDatasetMenu(self):
          
          enabled = True
          current = self.vtgui.dbs_tree_view.currentIndex()
          if current:
              leaf = self.vtgui.dbs_tree_model.nodeFromIndex(current)
              if leaf.node_kind in (u'group', u'root group'):
                  enabled = False
  
          self.plot_action.setEnabled(enabled)
docs: Update the `export` QAction when the Dataset menu is pulled down.
  
          This method is a slot. See class ctor for details.