When importing document containing a destination which points to invalid page reference, KeyNotFoundException is thrown.

RadPdfViewer can not find startxref keyword at the end of a document if the document contains many zero bytes at its end. NotSupportedException is thrown with "Startxref keyword cannot be found" message. 

Workaround: Trim the ending zero bytes before loading the document to the PdfViewer. This is currently noted in the WinForms KB article:
http://www.telerik.com/support/kb/winforms/details/notsupportedexception-startxref-keyword-cannot-be-found-when-loading-pdf-file-in-radpdfviewer-for-winforms

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.

When modifying Interactive Forms TextBoxField's value the entered changes are preserved after is clicked out of the TextBoxField's editing area. However the changes are not applied when the click is performed on the save button.

As possible workaround you can raise a MouseLeftButtonDown event on the RadPdfViewer and after this execute the SaveAsCommand. For example:

private void SaveButton_Click(object sender, RoutedEventArgs e)
{
    MouseButtonEventArgs mouseEventArgs = new MouseButtonEventArgs(Mouse.PrimaryDevice, 0, MouseButton.Left)
    {
        RoutedEvent = FrameworkElement.MouseLeftButtonDownEvent
    };
 
    ((FrameworkElement)this.pdfViewer.FixedDocumentPresenter).RaiseEvent(mouseEventArgs);
    this.pdfViewer.CommandDescriptors.SaveAsCommandDescriptor.Command.Execute(null);
}

When Find Next is used multiple times fast, and pages are still loaded asynchronously, sometimes NullReferenceException is thrown with the following call stack:

System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.GetLastCharacter()
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.IsLineBreak(Glyph glyph)
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.ProcessGlyph(Glyph glyph)
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.CreateTextPage(RadFixedPageInternal page)
   at Telerik.Windows.Documents.Fixed.Text.TextDocument.GetTextPage(Int32 index)
   at Telerik.Windows.Documents.Fixed.Search.KMPTextSearch.FindNext(TextDocument document, TextPosition startPosition, String searchText, Boolean matchCase, Boolean wholeWordsOnly)
   at Telerik.Windows.Documents.Fixed.Search.TextSearch.Find(String text, TextSearchOptions options)

...

Usually, the entries are on neighboring rows. However, some producers introduce some extra blank rows between entries and this causes exception in RadPdfViewer implementation.

Fix available in R2 2018 SP1 release version.

The issue is reproducible only on Windows XP. On newer versions of windows, the images are rendered as expected.

WORKAROUND: You may inherit DctDecode class in order to implement custom decoder. For instance, you may try calling DecodeWithJpegDecoder method from the base class as mentioned in the note of this documentation article:

http://docs.telerik.com/devtools/wpf/controls/radpdfviewer/customization-and-extensibility/customize-pdf-rendering

A sample implementation of these custom decoder may be seen below:

public class CustomDctDecode : DctDecode
{
    public override byte[] Decode(PdfObject decodedObject, byte[] inputData, DecodeParameters parms)
    {
        return DecodeWithJpegDecoder(inputData);
    }
}

The width values from the widths PDF property should be taken with priority compared to the font file calculations.

Fix available in R2 2018 SP1 release version.

This is reproducible for images with FlateDecode and predictor value in the range between 10 and 15. As an example you may take a look at the DecodeParms property in the following image PDF dictionary:

<< /BitsPerComponent 8 /ColorSpace /DeviceRGB /DecodeParms << /BitsPerComponent 8 /Colors 3 /Columns 1024 /Predictor 15 >> /Filter /FlateDecode /Height 2868 /Subtype /Image /Type /XObject /Width 1024 /Length 1236707 >>

Currently the minimal zoom out value is 0.8% which impacts the performance while scrolling large documents.

This is caused by an incorrect order of applying the TextMatrix and the glyph stroking operation.

When ScaleMode is set to FitToPage scrolling the Mousewheel or pressing the Arrow Down button does not produce immediate scroll. The page is scrolled to the next page after several scroll events/button presses are introduced.

Workaround: Provide custom ScrollCommand implementation.

This is reproducible when the matched result resides on different page.

Workaround: You may subscribe to the RadFixedDocument.CaretPosition.PositionChanged event and implement the scroll logic. Subscribe to PdfViewer's DocumentChanged event first if the document is not loaded.
        private void CaretPosition_PositionChanged(object sender, EventArgs e)
        {
            Telerik.Windows.Documents.Fixed.Model.RadFixedPage currentPage = this.pdfViewer.Document.CaretPosition.Page;
            int pageIndex = this.pdfViewer.Document.Pages.IndexOf(currentPage);
            this.pdfViewer.GoToPage(pageIndex + 1);
        }

Currently, we use System.Windows.Controls.TextBox for editing both TextBox and CombTextBox field types. We should implement CombTextBox editor which would allow having spaces between characters during the editing process.

RadPdfViewer's AcroForm property ViewersShouldRecalculateWidgetAppearances should be respected when being set to true. In this case, RadPdfViewer should recalculate all widget appearances and this would resolve the issue with empty form field widgets after opening such PDF document.

This would allow switching the focus between form field controls by using the Tab key.

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. 

At this point, the Print() method allowing the customers to silently print a document uses the PrintableAreaWidth and PrintableAreaHeight properties of the print dialog, which are read-only and cannot be changed through the API. Consider changing them with PrintTicket.PageMediaSize.

We should also consider the scenario when the client needs to print a smaller PDF page on a bigger page size. For instance, A5 page to be printed on an A4 sheet without scaling the content.

An ArgumentException is thrown internally as the font name is null. However, the name is defined in the base font and can be obtained from it.

Fix available in LIB Version 2018.1.402.

Currently, RadPdfViewer uses default constant value for the font size in this scenario.