If you’re having problems with your Undo Levels being reset to zer0, it could be a C++ plugin that’s doing it (or less likely, a NetView page). C++ plugins (and NetView pages) that set the Undo Levels to 0 and then don’t restore it, either by oversight or because of a crash/error, can leave you with your Undo Levels set to 0.
In constrast, we prevent scripts and script-based plugins from changing the Undo Level permanently: as soon as the script finishes execution, Softimage resets the General.undo preference to its default value.
For example, if you run this in the script editor:
Application.SetValue("preferences.General.undo", 0, "")
You’ll see this logged in the script history:
# VERBOSE : Restoring preference changed by script: General.undo