When stacking a bar chart, you often want to see the resulting sum of the
different groups (esp. if there are negative values). For example, when
displaying a stacked chart of invoices vs credit notes, you usually also
want to know the net total.
This is done only on stacked bar charts that have single column per
x-axis label and with more than one level of groupby.
closesodoo/odoo#114132
Task-id: 3193260
Signed-off-by: Mathieu Duckerts-Antoine <dam@odoo.com>
Joseph Caburnay
b03cfce033