def focus_next(self):
        """move focus to next position (DFO)"""
        w, focuspos = self.get_focus()
        next = self._tree.next_position(focuspos)
        if next is not None:
            self.set_focus(next)
def focus_next ( self ) : w , focuspos = self . get_focus ( ) next = self . _tree . next_position ( focuspos ) if next is not None : self . set_focus ( next )
move focus to next position (DFO)