Hi ​@Hans-Jürgen Feige 

What OpticStudio version are you using? In 20.3.2 (my version), I cannot adjust it through the API. You can access TheApplication.Preferences.General, but for me, Undo is not exposed.

If you use Standalone mode, you could use the code of Example 26 of ZOSAPI help:

TheConnection.PreferencesFile = 'path_to_file.cfg'
TheApplication = TheConnection.CreateNewApplication()

But I guess that does not work for extension mode (as the application is already up and running). Unless Undo is exposed in newer versions of the API, you will have to set it manually to None before connecting. 

Hi Luc, thanks for your answer.

Setting this option manually is not a handy solution for an interactive extension used by optical designers in process.

Users do not use programs that require them to configure everything beforehand.

It's also a security issue if they forget to turn it back on.

It is simply not understandable why not all settings are available via API.

This prevents acceptance.

Greetings Hans-Jürgen