I am required to use Pharo for a OO class project. In short, my project is to build a simple UML editor which allows a user to share his/her design with other users in real-time. I have chosen to do this in Morphic.

I am looking for guidance/best practices for the following:

Is there a recommended pattern to structuring the application. Should all my application objects be derived from Morph objects? Or should a morph be composed within my own domain objects and use morphs for the visual part?

Any guidance on proper mouse handling techniques. Which methods to override. Writing event-handlers, etc.

How can I achieve multiple inheritance. For example, I want all my drawing objects (use case, class, actor, etc.) to derive from a common class but at the same time each drawing object seems to be a natural extension of an existing morph. For example, use case can derive from�EllipseMorph, class can derive from�RectangleMorph, etc.

Are there any similar applications in SqueakSource which I can look at to get some guidance.

Thanks.