pyside tr() does not support inheritance

def tr(self, msg, arg2=None, arg3=None):
    """
    @brief Reimplement Qt's tr() function so translations can be found for
           strings defined in a base class, but displayed by an instance of
           a derived class.
    @param msg  The sourceText to translate.
    @param arg2 The optional disambiguation text, or a comment to the
                translator.
    @param arg3 The optional number to use for determining a plural form
                of the translation.
    """
    # The import is here just to keep all aspects of this hack inside the
    # function.  We need the name of the calling function in order to
    # determine which superclass actually implements it.
    import inspect
    caller = inspect.stack()[1][3]
    context = None
    for klass in self.__class__.mro():
        if caller in klass.__dict__:
            context = klass.__name__
            break

    # Call the application translation function.  There doesn't seem to be
    # a way to pass the context string to QObject's tr(); it is always
    # extracted from the name of self's type.  The QCoreApplication
    # translate() adds an extra argument, and I don't trust the PySide
    # docs' specification of default arguments, so I'm being very explicit
    # in passing only the arguments passed to this function.
    qApp = QCoreApplication.instance()
    if arg3:
        return qApp.translate ( context, msg, arg2, n=arg3 )
    elif arg2:
        return qApp.translate ( context, msg, arg2 )
    else:
        return qApp.translate ( context, msg )