background_color becomes white after mutating animals (basic_table_color example)

[chip]

Hi, To demonstrate this unexpected behavior, I've made a small change below the cell_rows declaration to examples/basic_table_color.rb in 0.12.6:

        on_row_clicked do
          animals << AnimalPresenter.new('sheep', 'bah', true)
        end

Running the example displays as expected:

However, after clicking a row, the background color is set to white:

I'm not sure if this is a bug, but it was unexpected. Is there a way to have background_color called to refresh the table colors? Thanks in advance.