Hi Piotr,
Greetings from Syncfusion.
At present, we do not have support to “Events for tracking the changes made in annotations”. We have already added it to our feature request list. But we do not have any immediate plans to implement this feature. At the planning stage for every release cycle, we review all open features. We will let you know when this feature is implemented. We usually have an interval of at least three months between releases. The feature implementation would also greatly depend on the factors such as product design, code compatibility and complexity. You can now track the status of this feature request here,
Kindly share us the more details of your requirement on this feature, so that we will consider it while implementing this feature in PdfViewerControl
Regards,
Uthandaraja S