The object definitions are split into several lines:

Creating a PdfViewer instance without adding it in the visual tree, leads to leaked document presenter instances when the TouchManager is enabled.

Workaround: Disable the TouchManager:

Telerik.Windows.Input.Touch.TouchManager.IsEnabled = false;

Currently, the PdfProcessing document model is providing support only for a single function in the Function entry.

According to the PDF Specification: Function: A 1-in, n-out function or an array of n 1-in, 1-out functions.

According to the PDF specification (Adobe® Portable Document Format Version 1.7):
Append a rectangle to the current path as a complete subpath, with lower-left corner (x, y) and dimensions width and height in user space.

The operation: 

x y width height re

An invalid case:

0 - 595 -842 re

This leads to an exception thrown: System.NullReferenceException: 'Object reference not set to an instance of an object.'

Hi Telerik Support

We use your Telerik PDF-Viewer since your last Version "UI for WPF R1 2021" which supports Type 3 fonts.
Now the version runs productive by our customers. But after a day, they found some special PDFs that doesn't work quite right with your PDF-Viewer.

In the appendix you will find the PDf-Files as samples for the bugs that i'm describing.
Because of data privacy, the PDF-Files are cutted and cropped.
Also a demo project is appended (It could also be reproduced with the demo Progress Telerik WPF UI for th PDF-Viewer).

First Problem: Blank Page

Hint: It seems that only a few PDF-Files from a specific program seems to be a problem.

1. Open Demo "WpfAppPdfViewer.exe"
2. Open the file sample_1_blank_page.pdf(see appendix)
3. You will see only a blank page
4. Open the same PDF-File in another PDF-Reader like Adobe Reader and you will see a scan with an illegible stamp of an address

Second Problem: Displaying data delayed

1. Open Demo "Progress Telerik UI for WPF"
2. Open the file sample_2_delayed_display.pdf (see appendix)
3. You will see only a blank page
4. Wait approx. 5-10 sec. and you will see the content of the PDF-File.

I would be glad for a quick possible solution for our customer.

Best regards

Serge Schoop

When importing a document containing Outlines (Bookmarks) containing Actions with an empty dictionary:

<</Title(Bookmarks)/Parent .../First .../Last .../Prev .../A<<>>/Count ...>

leads to an exception thrown: System.MissingMethodException: 'Cannot create an abstract class.'

From the PDF specification:

Prev: (Present only if the file has more than one cross-reference section; must not be an indirect reference) The byte offset from the beginning of the file to the beginning of the previous cross-reference section. 

When importing such a document an exception is thrown: System.ArgumentNullException: 'Value cannot be null.