There have been some issues with ExtendedDataTable with a4j. Check the Richfaces forum and JIRA.
I'm doing stuff with rich:extendedDataTable components. I'm using the 3.3.0.GA version and have used it with both of toe latest GA versions of Seam. I'm using the
onSelectionChangeas my a4j:support event.
I don't know whether or not it matters, but I'm explicitly setting bypassUpdates to
true. I'm not using a header facet. (That really shouldn't matter.)