The problem I'm trying to solve is that users do not know that the original document may not be what they are seeing in the viewer when there are layers.    

A property that indicates that a document has layers would allow the system to refuse to open the document.

Open the Demo app and load the PDF document with such annotation. The following error occurs:

RadPdfViewer can not display annotated PDF file
 Kindly,i used VintaSoft SDk to Annotate PDF File, File is annotated successfully and i can open it with Adobe Reader and see annotations is added to it
 but while i try to view annotated PDF file using RadPDFViewer File will displayed without annotations ,only original content displayed.
Kindly find my attached AnnotatedPDFfile To be loaded in RadPDfViewer

The attached file lorem-ipsum.pdf is rendered incorrectly in PdfViewer. I suspect it has something to do with kerning, because monospace font is not affected. Adobe Acrobat, Foxit PDF Reader, and Chrome render the file correctly.

The file was created with Pandoc, open source software, converting a markdown file (.md) to .pdf.

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 '.', ':', '(', '...'

Also, the CaretPosition is not correct.

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

WORKAROUND: You may try implementing custom filter that handles the CMYK scenario. How to implement custom DCTDecode filter is described in this documentation article:
https://docs.telerik.com/devtools/winforms/pdfviewer/customize-and-extensibility/customize-pdf-rendering

Steps to reproduce:

1. Load a PDF document with 0 pages

2. Enter some text in the search textbox and click the next/prev buttons

Expected: the search textbox should be either disabled or should ignore any search operation

Actual: an error occurs

Workaround:

    Private Sub pdf_Viewer_DocumentLoaded(sender As Object, e As EventArgs)
        If pdf_Viewer.Document.Pages.Count = 0 Then
            pdf_Toolbar.SearchTextBox.Enabled = False
            pdf_Toolbar.NextButton.Enabled = False
            pdf_Toolbar.PreviousButton.Enabled = False
        Else
            pdf_Toolbar.SearchTextBox.Enabled = True
            pdf_Toolbar.NextButton.Enabled = True
            pdf_Toolbar.PreviousButton.Enabled = True
        End If
    End Sub