The visualizations of all annotations are defined by their normal appearance streams. This is already implemented in RadPdfViewer for the supported annotation types (Link and Widget annotations). It may be easily adopted for not supported annotation types as well.

Available in 2017 R3 Official Release Version.

The redaction annotation is described in the following PDF reference document:
http://www.adobe.com/content/dam/Adobe/en/devnet/acrobat/pdfs/pdf_reference_addendum_redaction.pdf

You may also see sample document with this annotation type attached.

Since LIB Version 2017.3.925 annotations of type Redact can be visualized.

Loading page with a lot of text takes several minutes which is unacceptable. This performance issue is caused by class GlypInfoFactory, which caches the glyph information.

Available in LIB Version 2017.3.1225.

When a PDF is printed all images are omitted.

Available in R1 2018 SP1 version.

This happens only in specific scenarios as most of the documents with annotations are visualized correctly.

This action is usually linked to a Button field and with it, the user of the application may revert all field values to their defaults. 

When the Interactive Form Fields are in read-only mode, the user should not be able to change the value of the field. The associated Form Field widgets should not interact with the user, e.g. they should not respond to mouse clicks or change their appearance in response to mouse motions.

It seems that the glyph outlines are rendered wrong for some specific CFF font files. For instance, the issue is reproducible with "Aleo-Light" font.

When the file has an annotation with a destination and this destination is missing from the destinations (Dests) collection of the catalogue, KeyNotFoundException is thrown when you try to scroll to the page where the annotation is located. A better behavior would be for nothing to happen when trying to click on the annotation leading to the destination.

When RadPdfViewer is in text selection mode and the user is trying to select a word by double-clicking on it, the last letter of the word is not selected when the word is followed by some symbols like '.', ':', '(', '...'

In the PDF document model, the Annotation appearances refer to an external resource using the Resources dictionary. When the Resources dictionary is defined as an Indirect Object an InvalidCastException: 'Unable to cast object of type 'Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Types.PdfDictionary' to type 'Telerik.Windows.Documents.Fixed.FormatProviders.Pdf.Model.Elements.DocumentStructure.PdfResource'.', is thrown.

We should implement the logic for getting character codes from Unicode when using CFFFontSource.
Workaround: The font may be changed by creating a similar font with FontsRepository.TryCreateFont(...) method.

Telerik.Windows.Zip.InvalidDataException for unknown (0xAD) compression method is thrown for some object streams.

Loading document containing link with no destination leads to ArgumentNullException in PdfElementToFixedElementTranslator.CreateDestination method.

Documents containing large images are slow to decompress and decode.

Unsupported annotations are rendered on top of other content. When there is a form field that appears inside the annotation, it cannot be clicked or interacted with as the annotation is capturing the mouse gestures.

When the font is not embedded in the document, PdfViewer tries to read it from the OS. However, the Calibri-Font is not properly parsed and a NullReferenceException is thrown internally for its encoding. 

The offset of the Page boundaries such as CropBox, MediaBox, BleedBox, and ArtBox is not respected and is always treated as 0 which causes misplaced Annotations.

This is Unicode (UCS-2) encoding for the Adobe-GB1 character collection.

Described on page 443 in Pdf Reference 1.7.