Hi,

It depends on what changes you are interested in. If you are interested in any change of the drawing document, you can check the value of its IsModified property.

If you are interested only in moving, resizing and rotating of shapes, then you can subscribe to the NodeBoundsChanged event of the drawing document's even sink service:



If you are interested in any property change then you should subscribe to the NodePropertyChanged event of the drawing documents even sink service:

document.EventSinkService.NodePropertyChanged += OnNodePropertyChanged;
private void OnNodePropertyChanged(NNodePropertyEventArgs args)
{
    string changedPropertyName = args.PropertyName;
}

Best Regards,
Nevron Support Team