Re: Treeview item indicators in image-based themes vs Tk 9

In tcl/tk 8.6, the styling for these indicators are usually done via
something like this:
 ttk::style element create Treeitem.indicator \
               image [list $image_for_closed \
                   user1 $image_for_open \
                   user2 $image_for_no_children \
               ] ...
 But this doesn't seem to work in tk 9: now all items have an indicator
showing the image_for_closed whether they have children or not, and
whether the item is opened or not.
 I suspect a change in the names for the states "user1" and "user2" - which
were admittedly not very user-friendly - but I just can't find any
reference for these, and by what I should replace them in tk 9 if that's
indeed the problem.