give this model some filtering capabilities. We might add a string-list of object types to reject, and object types to accept. Right now, down in setupModelData, a simple filter is being applied to reject any object that does not carry a Q_CLASSINFO of "DESIGNABLE". This is simple and fairly rudimentary but its capabilities should probably be expanded to make this model a little more general purpose. For instance, a filter could be set up so that only objects shown are those that are inherited from a particular base class... all kinds of possibilities.