I have ported the existing Qt(3) backend to Qt4. Qt4 is a substantial
change from Qt3; the Python bindings for Qt have also changed
substantially. Since the two versions of Qt are likely to coexist for at
least a while, I think it makes sense to have a separate Qt4 backend.
How do I go about contributing my Qt4 backend? I have three files:
backend_qt4.py, backend_qt4agg.py and embedding in qt4.py.