Added to the top level report in https://github.com/piwik/piwik/commit/237f202c7a4ac7b659855d3078ae5a58c1ee3c65
It's not possible to add it subtables w/o requesting the top-level report in the subtable API method. This would be a performance hit so I'm moving this to 3.0.
For 3.0, we should make it possible for idSubtables to be the parent row's label, instead of just an integer ID. This would make it possible to get the row label within the subtable method and would increase performance in some cases when it is required to get a subtable by row, w/o having querying the parent table first.
Moving back to 2.15.0 - let's close this issue as this is already a new feature, we'll open a new one for the sub-tables icon.
So then should this be closed?
This enhancement already is useful, nice :+1:
Will be followed up & improved further in #8837