Run the project and load a document with bookmarks. Try to click the two buttons in order to switch between thumbnails/bookmarks. 

        private void radButton1_Click(object sender, EventArgs e)
        {
            this.radPdfViewer1.ShowThumbnails();
        }

        private void radButton2_Click(object sender, EventArgs e)
        {
            this.radPdfViewer1.ShowBookmarks();
        }

Expected: clicking the two buttons should switch between bookmarks/thumbnails

Actual: the user is stuck to bookmarks

With the R1 2021 version of our controls RadPdfViewer is using the RadPdfProcessing library model. In this scenario, the PDF document contains images with sizes 87380, 87654. Internally the control is using RenderTargetBitmap to draw the image. So when we pass these values as Width and Height to the constructor of this object an exception occurs. This is a limitation of the RenderTargetBitmap class. It can be reproduced outside of the RadPdfViewer.

RenderTargetBitmap bmp = new RenderTargetBitmap(87380, 87654,96,96,PixelFormats.Pbgra32);

As a workaround, we can use the old rendering engine of the control by setting the RadPdfViewer.UsePdfProcessingModel property to false. 

When exporting a RadFixedDocument, which contains a signature added with PdfProcessing a NotSupportedException is thrown: 'Stream does not support reading.'

Resolution: When exporting a digitally signed document a stream that allows both reading and writing should be passed to the PdfFormatProvider.

Example:

Stream outputStream = new FileStream("path", FileMode.OpenOrCreate, FileAccess.ReadWrite)

The highlight annotation appears above the text and covers it, instead of appearing under it.

Expected:

Actual:

Hello 

I am have a problem with pdf wiewer when the PDF file contains an images , it is slow in movement and it is difficult to navigate between pages. Is it possible to fix this problem