How to reproduce: create a document like the one below, then try to add a comment  for an element in the paragraph with the bookmarks
Public Class Form2
    Sub New()

        InitializeComponent()

        Dim document As New RadDocument()
        Dim section As New Section()
        Dim paragraph As New Paragraph()
        Dim span As New Span("Content prior range[")
        Dim span2 As New Span("]Content after range")
        Dim readOnlyContent As New Span("READ ONLY")
        Dim rangeStart As New ReadOnlyRangeStart()
        Dim rangeEnd As New ReadOnlyRangeEnd()
        rangeEnd.PairWithStart(rangeStart)
        paragraph.Inlines.Add(span)
        paragraph.Inlines.Add(rangeStart)
        paragraph.Inlines.Add(readOnlyContent)
        paragraph.Inlines.Add(rangeEnd)
        paragraph.Inlines.Add(span2)
        section.Blocks.Add(paragraph)
        document.Sections.Add(section)

        Dim bmSection As New Section()
        Dim bmParagraph As New Paragraph()
        Dim bmSpan As New Span("Content prior bookmark[")
        Dim bmSpan2 As New Span("]Content after bookmark")
        Dim bmContent As New Span("Content in Bookmark")
        Dim bmRangeEnd As New BookmarkRangeEnd()
        Dim bmRangeStart = DirectCast(bmRangeEnd.CreatePairedStart(), BookmarkRangeStart)
        bmRangeStart.Name = System.Guid.NewGuid().ToString()
        bmParagraph.Inlines.Add(bmSpan)
        bmParagraph.Inlines.Add(bmRangeStart)
        bmParagraph.Inlines.Add(bmContent)
        bmParagraph.Inlines.Add(bmRangeEnd)
        bmParagraph.Inlines.Add(bmSpan2)
        bmSection.Blocks.Add(bmParagraph)
        document.Sections.Add(bmSection)

        Me.RadRichTextEditor1.Document = document

    End Sub
End Class

Workaround: To clear a given property, basing on some logic which determines if it should be cleared. For example
this.radRichTextEditor1.CommandExecuting += (s, e) =>
{
    if (e.Command is ChangeStyleNameCommand)
    {
        var style = this.radRichTextEditor1.Document.StyleRepository.GetValueOrNull(e.CommandParameter.ToString());
        if (style.Type == Telerik.WinForms.Documents.Model.Styles.StyleType.Paragraph)
        {
            Paragraph paragraph = this.radRichTextEditor1.Document.CaretPosition.GetCurrentParagraphBox().AssociatedParagraph;
            foreach (Span span in paragraph.EnumerateChildrenOfType<Span>())
            {
                span.ClearValue(Span.FontFamilyProperty);
                span.ClearValue(Span.FontSizeProperty);
            }
        }
    }
};

There is an issue with the way the editor decides what width to render a table.

The example I have encountered is in an HTML email from Outlook that contained a table. Whatever way Outlook composes the HTML, it adds a width attribute and a style attribute to the table's opening tag:

<table width="0" style="width: 500px;">

In this situation, the inline style should take precedence over the width attribute (the width attribute is actually deprecated as of HTML5). This is how all common browsers behave.

You can see in the attached 1_browser.png that Chrome correctly renders the table at 500px;

However the RadRichtextEditor component incorrectly renders the table at width 0 as shown in attached 2_RadRichtextEditor.png, ignoring the width specified in the style attribute.

Curiously, other CSS rules in the style attribute are correctly interpreted.
For example:

<table width="0" style="width: 500px;font-weight:bold;">

will display a table of zero width with bold text in the RadRichTextEditor.

Thanks guys!

Add support for All Capitals (All caps) and Small Capitals (Small caps) run property. MS Word has such option in Home -> Font -> Dialog Launcher -> Font -> All Caps/Small Caps.

All letters of such runs are visualized as capital letters.

The corresponding elements in OOXML are <w:caps /> and <w:smallcaps />.

Pressing Tab/Shift+Tab when caret position is at the beginning of a paragraph should change current paragraph FirstLineIndent instead of LeftIndent.

First line indent should be changed to Document.DefaultTabWidth step.

Workaround:
private void RadRichTextEditor1_KeyDown(object sender, KeyEventArgs e)
{
    if (e.KeyData != Keys.Tab)
    {
        return;
    }

    this.radRichTextEditor1.Insert("\t");
    e.SuppressKeyPress = true;
    e.Handled = true;
}

Workaround: Handle the CommandExecuted event and change the font family after executing the paste command:

private void RadRichTextEditor1_CommandExecuted(object sender, Telerik.WinForms.Documents.RichTextBoxCommands.CommandExecutedEventArgs e)
{
    if (e.Command is PasteCommand)
    {
        foreach (var p in this.radRichTextEditor1.Document.EnumerateChildrenOfType<Paragraph>())
        {
            if (p.IsInList)
            {
                var list = this.radRichTextEditor1.Document.ListManager.GetDocumentListById(p.ListId);
                list.ActualStyle.Levels[0].FontFamily = new Telerik.WinControls.RichTextEditor.UI.FontFamily("Symbol");
            }
        }
    }
}

How to reproduce: check the attached gif file

When the content of an entire row is copied and the caret is inserted in the left most column of a row, then the content of each cell in that row should be overwritten with the contents in the clipboard when pasted.

When such content is pasted just after a table, new row is added and filled with values.

When such content is pasted in paragraph, new table is created.

To reproduce: run the project, load the document available in the project's folder and start clicking the words. You will notice that the cursor is shifted on the right. 

Workaround: don't enable the RightToLeft property.

When there is a hyperlink enclosed in another annotation (e.g comment, bookmark, read-only range), and the user moves the caret position just before or just after the hyperlink, and starts typing there, the text is inserted with the style of the hyperlink (by default, blue with blue underline). Instead, the text should be inserted without such style.

Applying negative LeftIndent or FirstLineIndent of a paragraph in web layout mode will visualize the paragraph to the left of RadRichTextBox boundaries.

<samp> HTML element could be imported as span with specific formatting. Currently it's just ommited.

Currently unknown/unsupported elements are skipped, which potentially loses text content. Consider adding setting in HtmlImportOptions allowing the phrasing content (text) of these elements to be imported. 

Sample HTML:

<html>
<body>
<test-test>test-test</test-test>
<body/>
</html>


Browsers visualize it as "test-test", while RadRichTextBox doesn't import anything.

MS Word imports such elements as inline elements (just like spans).

When the rtf document contains a table as the one below and the empty declaration is used in the following structure, the document cannot be imported:

{\fonttbl
{\f0 Verdana;}
{\f1 Times New Roman;}
{\f2 ;}
{\f3 Segoe UI;}}

See attached!