There appears to be an issue when adding Comments that overlap each other. I will attach a video to my next reply that shows how to replicate the issue.

Copy some text from the introduction docs page:

Paste in RadRichTextEditor from the Demo app:

 

When I have an InlineImage in a horizontally centered paragraph, PrintPreview presents the image unevenly on the page. There should be the same space on left and right, as the page padding is the same all around. See the arrows indicated below:

 The scroll is jumping when making a selection and reaching the end of the document (see attached)

Workaround: load an empty docx document in the RadRichTextEditor and use it as a template
public RadDocument ImportDocx()
{
    RadDocument document = null;
    IDocumentFormatProvider provider = new DocxFormatProvider();
    OpenFileDialog openDialog = new OpenFileDialog();
    openDialog.Filter = "Documents|*.docx";
    openDialog.Multiselect = false;
    DialogResult dialogResult = openDialog.ShowDialog();
    if (dialogResult == System.Windows.Forms.DialogResult.OK)
    {
        using (Stream stream = openDialog.OpenFile())
        {
            document = provider.Import(stream);
        }
    }
    return document;
}

To reproduce:
- Add a word, press tab the add another word.
- Export the document using HtmlFormatProvider.
- Import the same document.
- The tab is interpreted like 7 spaces. 

To reproduce: please refer to the attached sample project.

Workaround: export RadRichTextEditor's content to a .doc file. Then, use the RadWordsProcessing library to import the .doc file and export it as a pdf:

Telerik.WinForms.Documents.FormatProviders.OpenXml.Docx.DocxFormatProvider provider = 
    new Telerik.WinForms.Documents.FormatProviders.OpenXml.Docx.DocxFormatProvider();
string fileName = @"..\..\exported.doc";
string pdfFileName = @"..\..\exported.pdf";
Stream s = new FileStream(fileName,FileMode.Create, FileAccess.Write);
provider.Export(document, s);
s.Close();
s.Dispose();

Telerik.Windows.Documents.Flow.FormatProviders.Docx.DocxFormatProvider provider2 = 
    new Telerik.Windows.Documents.Flow.FormatProviders.Docx.DocxFormatProvider();
using (Stream input = File.OpenRead(fileName))
{
    Telerik.Windows.Documents.Flow.Model.RadFlowDocument document2 = provider2.Import(input);
    Telerik.Windows.Documents.Flow.FormatProviders.Pdf.PdfFormatProvider provider3 = 
        new Telerik.Windows.Documents.Flow.FormatProviders.Pdf.PdfFormatProvider();
    using (Stream output = File.OpenWrite(pdfFileName))
    { 
        provider3.Export(document2, output);
    }
}

System.Diagnostics.Process.Start(pdfFileName);       

The equation objects in word document are not copied and imported correctly in RadRichTextBox

To reproduce:
Add image like this:
void button_Click1(object sender, EventArgs e)
{
    Section section = new Section();
    Paragraph paragraph = new Paragraph();
    ImageInline image;
    Telerik.WinControls.RichTextEditor.UI.Size size = new Telerik.WinControls.RichTextEditor.UI.Size(236, 50);
    using (MemoryStream ms = new MemoryStream())
    {
        System.Drawing.Image.FromFile(@"C:\img\delete.png").Save(ms, System.Drawing.Imaging.ImageFormat.Png);
        image = new ImageInline(ms, size, "png");
    }

    paragraph.Inlines.Add(image);
    section.Children.Add(paragraph);
    this.radRichTextEditor1.Document.Sections.Add(section);
}

Workaround:
Manually update the layout:
 this.radRichTextEditor1.UpdateEditorLayout();

To reproduce: create a Word document with a table. Design a more complex table with nested tables in each cell. Specify "None" border for the internal tables. When loading the document in the RadRichTextBox, the borders are displayed.

If you export a document using the HtmlFormatProvider, all style properties which contain measurement units are exported in pixel units. This makes the exported documents look much smaller when opened on devices with higher pixel density.

WORKAROUND: use Regex to find, convert and replace the font-size attributes

            HtmlFormatProvider html = new HtmlFormatProvider();
            string res = html.Export(document);
            Regex regex = new Regex(@"font-size: [0-9]*\.?[0-9]*px");
            Match match = null;

            do
            {
                match = regex.Match(res);
                if (!match.Success)
                {
                    break;
                }

                string value = match.Value.Substring("font-size: ".Length, match.Value.Length - "font-size: ".Length - "px".Length);
                double pts = double.Parse(value) * 72 / 96;
                res = res.Replace(match.Value, @"font-size: " + Math.Round(pts, 4) + "pt");
            } while (match.Success);

            File.WriteAllText("output.html", res);

To reproduce:

radRichTextEditor.Document = new RadDocument();
radRichTextEditor.Document.MeasureAndArrangeInDefaultSize();
radRichTextEditor.UpdateEditorLayout();
radRichTextEditor.Document.CaretPosition.MoveToLastPositionInDocument();

var p = new Paragraph();
p.Inlines.Add(new Span("Cell"));
var cell = new TableCell();
cell.Blocks.Add(p);
var row = new TableRow();
row.Cells.Add(cell);
var table = new Table();
table.Rows.Add(row);
var section = new Section();
section.Blocks.Add(table);
radRichTextEditor.Document.Sections.Add(section);
radRichTextEditor.Document.CaretPosition.MoveToLastPositionInDocument();

var provider = new RtfFormatProvider();
var txt = provider.Export(radRichTextEditor.Document);
Clipboard.SetText(txt, TextDataFormat.Rtf);

Workaround: measure the document after the section is added:
radRichTextEditor.Document.Sections.Add(section);
radRichTextEditor.Document.MeasureAndArrangeInDefaultSize();
radRichTextEditor.UpdateEditorLayout();

To reproduce:

1.Add some text to RadRichTextEditor.
2.Copy an image from a Word document and paste it to the RadRichTextEditor.
3.Export the document content with RtfFormatProvider.

When you try to open the exported .rtf file via WordPad, you will notice that the image is not loaded. Please refer to the attached files created by MS Word and RadRichTextEditor.

To reproduce:

public Form1()
{
    InitializeComponent();
    this.radRichTextEditor1.IsReadOnly = true;
}

Workaround:
private void Form1_Load(object sender, EventArgs e)
{
    this.radRichTextEditor1.IsReadOnly = true;
    Telerik.WinControls.RichTextEditor.UI.DocumentWebLayoutPresenter webLayoutPresenter = 
        this.radRichTextEditor1.RichTextBoxElement.ActiveEditorPresenter as Telerik.WinControls.RichTextEditor.UI.DocumentWebLayoutPresenter;
    webLayoutPresenter.Caret.Width = 0;
}

To reproduce:
Import the following rtf:
string rtfText = @"{\rtf1\ansi\ansicpg1252\deff0\deflang1031{\fonttbl{\f0\fnil\fcharset0 Arial;}{\f1\fnil\fcharset0 Tahoma;}{\f2\fnil\fcharset0 Times New Roman;}{\f3\fnil\fcharset0 Arial Unicode MS;}{\f4\fnil\fcharset0 Calibri;}}
{\colortbl ;\red0\green0\blue0;}
\viewkind4\uc1\pard\tx300\tx600\tx900\tx1200\tx1500\tx1800\tx2100\tx2400\tx2700\tx3000\tx3300\tx3600\tx3900\tx4200\tx4500\cf1\b\fs32 Arial\f1\par
Tahoma\par
\f2 Times New Roman\par
\f0 Arial\f2\par
\f3 Arial Unicode MS\par
\f4 Calibri\b0\f0\fs20\par
}";
RtfFormatProvider rtf = new RtfFormatProvider();
this.radRichTextEditor1.Document = rtf.Import(rtfText);

this.richTextBox1.Rtf = rtfText;

When highlighting text inside the richtexteditor control I receive a null reference exception.