Hi, I'm sorry for getting back late to you. We have never done this ourselves nor have we heard of anyone. The reasons for the difference between C++ and Python API are probably historic. Also back then we had no generic concept for callbacks in Python. Now, with MAXON API and appearance of Delegates and Observables such things will probably handled much nicer in future. Maybe it were also performance considerations. Many words, for a "I don't know", sorry. In any case we'll forward this a an idea to our development, so it is at least considered for a future release. Cheers, Andreas