There is a PythonQwt project.

Also, can you please tell me how to add child widgets to QGraphicsWidget?
QGraphicsWidget is a base class, meant to be derived from to add custom painting and other features. It isn't of much direct use as far as I can see. If you want to embed an existing QWidget in a QGraphicsScene, then QGraphicsProxyWidget is what you want. Otherwise, you have to dip into C++ and write your own.

If you don't need all of the signal / slot / event handling that QGraphicsWidget provides (by virtue of inheriting from QObject) and you want to write your own graphics, you should probably start by deriving from QGraphicsItem or one of its sub-classes.