I have a table with already calculated subtotals, which are not simple min/max/sum/avg function, but very complicated formula and can be calculated only from raw data. You can see example in attachment.
I want to use grouping feature, but when rows collapsed, i need to show pre-calculated subtotals.
It would be perfect, if it's can hide all lines except subtotal line, like excel doing, when group collapsed.
Is it possible to do with your library? If not - can you add such ability in next version?