docs: def treeWidgetChanged(self):
          """Called when this item is added or removed from a tree."""
          ParameterItem.treeWidgetChanged(self)
  
          # add all widgets for this item into the tree
          if self.widget is not None:
              tree = self.treeWidget()
              if tree is None:
                  return
              tree.setItemWidget(self, 1, self.layoutWidget)
              self.displayLabel.hide()
              self.selected(False)