'Handle data changes for node values.'

def update_properties(self):

    self._current_position = self.values.primary.data
    if (self.values.open and self.values.close and (self._open_id is None) and (self._close_id is None)):
        if self._invert_buttons:
            self._open_id = self.values.close.value_id
            self._close_id = self.values.open.value_id
        else:
            self._open_id = self.values.open.value_id
            self._close_id = self.values.close.value_id
