We needed the ability to show more details per row on the extended datatable so I added support for a details facet in the AbstractExtendedDataTable renderer.  If present, the renderer will render a hidden row of details after each row of data.  Your facet can then show more information about the current row.

Also we needed a totals footer at the end of grouped rows so I added yet another facet called "groupFooter" to the datatable.

The renderer renders this groupFooter as a TR with a TD colspanning the row containing the groupFooter facet contents.  It also renders a columnGroup as is with no additional TR since the column group encodes a TR anyway.

Before it renders the facet it can set a property on the backing bean containing the ordered list of rows for that group.  Your backing bean can then formulate a group total or whatever it wants with this group list.

I would recommend that changes like this go into the extended datatable proper.  We are currently building our own version of the table using a custom CDK project that is a copy of the original extended data table.

I can share our source code if there is interest but I really want to see this functionality go into the real table so we don't have to merge as updates come along.

I have attached the AbstractExtendedTableRenderer.java so you can see the changes I have made.  Look for //PTI:RSY for the changes.