Wrong color of lines due to Matrix Transformations applied to the Drawing.

PdfViewer: Invalid rendering with German culture (Regression). Some text is missing and the rendering is broken.

Some lines could be missing in the PdfViewer when rendering line geometries.

The attached image shows the issue.

The import performance is reduced and the memory consumption is increased when XObject instances have many Shading elements.

As a result, the glyphs are not measured and positioned properly. The issue applies to the TrueType and Type1 fonts.

Glyphs with specific font added to the document are not rendered. 

Layers represent groups of optional content which can be hidden or shown.

PdfViewer: The selected page is not synchronized with the selected index in the Thumbnail view when a document is opened manually. This issue occurs in the thumbnail example in the demo applicationl. 

A specific file is not displayed in the viewer.

Having a file with a very thin border thickness is displayed with increased thickness when displaying a document inside RadPdfViewer.

The default WPF PrintDialog cannot print asynchronously when it is shown in UI. However, you may see the demo in this forum post showing how to create custom PrintDialog and perform async printing with it:
http://www.telerik.com/forums/pdfviewer-print-makes-ui-unresponsive#js0YdzFWc0Oa8C3g6a18lg

Currently, the Save button of the RadPdfViewerToolBar element raises the SaveAsPdfDocumentCommand, which opens a new SaveFileDialog in its Execute method. We could raise an event there, in order for this action to be intercepted if the PDF file is saved.

When displaying PDF-Files using PDFViewer, ContentElementsCanvas .RenderAsync uses reflection (DispatcherObjectUtils.ApplyDispatcher) to render Visuals on multiple threads.
However this leads to a memory leak since the dispatchers cant be GC'ed, see screenshot below.




The Screenshot is from the actual application we expirienced this issue with, the attached reproduction example is a boiled down version of what your code does.
If you wanna reproduce this on your own, create an application that uses PdfViewer that switches between many pdf files. The ammount of Dispatchers will grow steadily, probably to a total of the number of threads used by Task.Factory.

Images hosted inside multiple Form XObjects are not rendered.

Some documents cannot be printed with the PdfViewer. In this case no exception is thrown and the result file is 0 bytes. 

When opening a document with a CFF Type1 font an exception is thrown: NullReferenceException: 'Object reference not set to an instance of an object.'

Represents Highlights PDF content. While the other annotations are drawn on top of the content, the highlight annotation is behind the text it highlights. In other words, it has to be inserted at a specific place in the ContentElementsUILayer. The precise place where the highlight should be placed is described in the PDF file with the BDC, MCID and EMC operators. At the moment, we have implemented a read-only rendering for all annotation types which draws the annotions separately from the page content. In the case of Highlight, the annotation is drawn below the other content. With this implementation, depending on the PDF content, the highlight annotation might be visible or it might not be because in some cases there is geometry content below the highlighted text which hides the highlight annotation appearance. 

A password is asked although Adobe opens the document without one when the document is encrypted with "Encryption of data using the RC4 or AES algorithms with a file encryption key length of 40 bits." - Version 1 (V 1) Revision 2 (R 2).

Similar cases (V1 R3 and V2 R3) are handled in the following item: PdfViewer: A password is asked although Adobe opens the document without one.

 Exception when rendering a file with a lot of RenderTargetBitmap objects (Com Exception: MILERR_WIN32ERROR). It seems that we are creating this for tilling patters which are not reused and we ca reconsider our appraoch.  

The text elements in a document are positioned wrongly and are slightly offset from their expected positions.