Restored Hugh's changes (commit a3c91c0 ) that I reverted in previous commit (in vain). Yes, they didn't work as expected, but the cause seems to be that the changes in form.php and group.php were missed.
The main goal is that if a group is not shown in form view then the form really doesn't try to update group's data and if in "details view only" mode then really shown in details + in list view). Although it was achieved without these modifications (in list.php, view.base.php and view.raw.php), they may be still necessary in some (unforeseen by me) situations (sorry, Hugh).