The component is complete :-) but I do understand your request and think it is a good one. Can you please create a jira at in our project jira - https://issues.jboss.org/browse/RF
Describing exactly what you are looking for. We'll review it and see if we can get it inot the next release - Roadmap and planning for RichFaces 4.1
I would be happy to create an enhancement request, however, there is already one in jira.
I don't agree with your statement that the work is complete on the extendedDataTable component. According to the 3.x to 4.0 migration documentation:
"And currently not implemented:
- Header menus from 3.3.x EDT component
- Visibility feature for columns"
The grouping functionality is in the above mentioned header menus. If the header menus were functional I could probably add an additional attribute to control the default grouping behavior (open/closed) as I did in 3.x, however, without the header menus I am stuck and will not be able to move the application to production using RichFaces 4.0. Do you have an idea when the header menus work will be complete?