'Override to update the item model and emit the signals.'

def _insert_category(self, desc):

    priority = desc.priority
    priorities = [c.priority for (c, _) in self.registry]
    insertion_i = bisect.bisect_right(priorities, priority)
    WidgetRegistry._insert_category(self, desc)
    cat_item = self._cat_desc_to_std_item(desc)
    self.__item_model.insertRow(insertion_i, cat_item)
    self.category_added.emit(desc.name, desc)
