Hello Philipp,

Thanks for getting back to us! Straight to your questions:

1)Obtaining the vertical offset and respectively scrolling to particular offset can be achieved in the following way:

2) Obtaining/setting the zoom level can be achieved using the ScaleFactor property of RadRichTextBox:
In this case Size(1,1) is equivalent to 100% zoom level.

3) Adding a bookmark from code is possible with the InsertBookmark() method:
You can then move the caret to the bookmark using its name by simply calling the GoToBookmark method of RadDocument or like this:

When it comes to your comment about RTF, I am afraid I am not sure what you mean. Could you give some kind of example so that we can better understand your needs?

I hope this helps! We're awaiting your reply.

Regards,
Petya
Telerik

Hello Philipp,

Thank you for providing us with additional details!

The scenario you wish to implement is not possible out of the box. However, what you could try is creating a custom annotation. For example, you could inherit the AnnotationMarkerBase class and create a simple marker-like annotation which does not require pairing like most other annotations in the context of RadRichTextBox. 

This setup would allow you to insert an instance of the marker at the caret position. Upon exporting the document, the marker will be preserved which would allow you to make modifications at its particular position. What you should be aware of in this regard is that custom annotations are only preserved when exporting to XAML format.

Additionally, I am not sure how you could go about wiring the logic inserting the annotation. Generally, if the class is called CaretPositionMarker, here is how you can add a marker at the caret position:
However, I'd not recommend placing logic executing this action in the PositionChanged event as the event is raised extensively when using RadRichTextBox and this might cause performance issues. In case you are using a data provider in your application you could set its UpdateSourceTrigger property to Explicit or LostFocus and only add the marker when updating the string (with the UpdateString() method of the provider). Please find attached a simple sample project demonstrating how this can be achieved.

I hope this helps! Let me know if I can provide further assistance.

Regards,
Petya
Telerik