applets/kickoff: Fix properties; Avoid creating invisible objects and menu items
- Don't rely on visible & enabled properties in dependent expressions
Their read values are transitive from parents.
- Avoid creating invisible objects and menu items
Using filtered models, it is possible to split systemFavoritesModel, so that Repeater and Instantiator would only have to deal with rows they really need.
Comments are reworded for clarity (which might be subjective).