Tk-multi-publish2 : Grouping collected items. Small UI question


We have customized the hooks of the tk-multi-publish2 app. We are grouping the items under a dummy group item. It works like I would expect. Double-clicking on the group expands it as expected, but there’s no arrow next to the group, so it’s not obvious for the artists that it can be expanded and that individual sub items can be activated/deactivated.

How can I add a little arrow there ?

Here’s the code that is creating the group ::

if len(all_caches) > 1:
            # More than one cache, we group the caches in the UI
            group_item_type = ""
            group_display_name = "{} caches".format(len(all_caches))
            group_type_display = "Multiple caches"
            # create the item
            group_item = parent_item.create_item(group_item_type, group_type_display, group_display_name)
            group_item.expanded = False
            group_item.set_icon_from_path(os.path.join(self.disk_location, os.pardir, "icons", "maya_multi_set.png"))
            # set the group item to be the parent
            parent_item = group_item