I would like to be notified in case the user changes the model unit system, resulting in scaling of the document objects.
The reason I’m asking this: I have custom user data (derived from ON_UserData) attached to certain document objects. This data would need to be scaled as well. According to my tests it seems that the scaling transformation resulting from a change of the model units is not recorded in ON_UserData::m_userdata_xform.
I have found the following event watcher, but don’t know how I would use it to detect changes of the module unit system:
void CRhinoEventWatcher::OnDocumentPropertiesChanged(CRhinoDoc& doc);