Qt Designer and subclassing QGraphicsView

From http://doc.trolltech.com/qq/qq20-jambi.html

The display is implemented by subclassing the QGraphicsView class. When using Qt Designer to create our user interface, this custom widget is unavailable to us. But it is still possible to include the widget in the user interface definition by "promoting" one of Qt's regular widgets as a placeholder for it on the form we create in Qt Designer.

So, when designing the user interface, we put a QGraphicsView widget onto the form, Then we open a context menu over it and click Promote to Custom Widget. In the dialog that opens, we specify the name of our subclass: QtanoidView in this case.