Has anyone been able to force TreeView expander with no children?

["Daniel B. Thurman" <dant cdkkt com>]

I have a FileViewer application that I am working on
and so far I have not been able to force expanders
on TreeView when there are only "top-level"
directories/files populated in the TreeStore.

You would think that doing something simple as:
[...]
self.treestore = gtk.TreeStore(str, gtk.gdk.Pixbuf, str)
self.treeview = gtk.TreeView(self.treestore)
self.treeview.set_show_expanders(True)
self.path = os.path.expanduser('~')
self.populate_treestore(path=self.path, recurse=0)
[...]

Would force the TreeView to show the expanders,
but I have not been able to get this to work.  I need
the expanders so that when I expand the directory
in question, I would then trigger a call to add more
children, and so on.

Any ideas?

Thanks-
Dan