def use_one_cell_anchor
      return if @anchor.is_a?(OneCellAnchor)
      new_anchor = OneCellAnchor.new(@anchor.drawing, :start_at => [@anchor.from.col, @anchor.from.row])
      swap_anchor(new_anchor)
    end
def use_one_cell_anchor
      return if @anchor.is_a?(OneCellAnchor)
      new_anchor = OneCellAnchor.new(@anchor.drawing, :start_at => [@anchor.from.col, @anchor.from.row])
      swap_anchor(new_anchor)
    end
Changes the anchor to a one cell anchor.