More pubsub calls

PubSub is a great Python package allowing you to decouple your objects from one another. I've changed Whyteboard to use more pubsub message passing instead of direct method invocation; it's allowed me to test the application easier and to also chain multiple actions from a single message (e.g. "change tab" updates the thumbnail, bolds its text and changes the notes' tree control selection

Eventually none of my objects will know about any of its interaction objects, except for the GUI, which will mediate method calls. Perhaps I could even put this mediator outside of the GUI so that the GUI only creates dialogs and other GUI components and handles menus' events by delegating it to another object


My main problem is the models sometimes need to know the state of the GUI or its sub-components: e.g. the canvas may wish to know if the drawing mode is set to transparent - which is stored in gui.util.

Eventually the canvas will have no reference to the GUI at all, so it needs to know a way to query the current state of the program. Hmm...