Set __properties before calling link/link_deps The alternative would be to make a post_init method, like link that is called after property is constructed.
Fix config.read() to call callbacks on all changes.
Add name attr to ConfigParser, name kivy and app config instances as such, and add method for ConfigParserProperty to register properties that use named config.
Set a ConfigParser for ConfigParserProperty using either a named config,or a config object, don't use property value for it anymore.