added a comment - There are facilities in the EditManager to recognize with a DataStore is requested; or perhaps even when one of the write methods are used; and enable the buttons at that time.
We had some problems (because FeatureSource does not have a setTransaction method) with using a FeatureSource for rendering; while editing with a FeatureStore and having the map out of sync. We "solved" them by requesting a FeatureStore first (ie all the time) and that is probably throwing the button enablement off.
We should be able to look at the BasicFeatureRenderer and turn off this "fix" now that we have some time. We can also go about adding featureSource.setTransaction - if it has not been done already.