Designing a QGraphics view framework application

[regular]

Hi, I have a code design question.

When creating an application with QGraphicsView and QGraphicsScene, is it bad design to let the scene handle user interface issues (like opening QDialogs or QWizards) and handle mouse events? In my case I need the user to specify some properties of QGraphicsItems before creating them by filling in a QWizard and later modify these properties by using a QDialog - where should this be handled?

Also, in the Diagram scene example for the QGraphics view framework, the QGraphicsItem context menus are all handled by the QMainWindow - is this a good approach?

What if I want a double click on a QGraphicsItem to open a dialog? Would the item need to know about dialogs?

Any other tips when designing such an application?

Thanks in advance.