Qt for Python (PySide/Shiboken)

QML is an independent language. PySide wraps the Qt/C++ libraries, if you found a problem with the same python code and exact qml code, it's probable that the issue lies underneath and it's related to Qt/C++ or the QML language itself, and not Python nor PySide. It would be better for you to share on the forum the Python code that you are using related to the handler, otherwise people cannot reproduce it.