807: Highlights

VisualWorks offers the Model, DependentPart, View, and Controller classes. The View class is a subclass of the DependentPart class.
If you want a dependent part or view to depend on a particular model, then instantiate one of the following patterns:
```
dependent part model: model 
view model: model 
```
If you want a model to broadcast an update: message to all its dependents, then send a changed: message to the model.
If you want a dependent part to respond to an update: message, then define update: for the dependent part's class.
If you want to obtain the model inside a viewer method, then send the model message to self.
If you want a controller to work with a particular model, then instantiate the following pattern:
```
controller model: model 
```
If you want to obtain the model inside a controller method, then send the model message to self.