Launch the RichTextEditor and observe the button are not completely visible and some/ most of the dialog boxes cannot be re sized.
--> Home Tab
1) Find/ Replace dialog box, button overlap the textboxes behind them
2) Change Styles , this dialog box cannot be re sized currently 

-->Insert Tab
1) Hyperlink dialog box, this dialog box cannot be re sized currently 
2) BookMarks dialog box, this dialog box cannot be re sized currently
3) Cross Reference dialog box, this dialog box cannot be re sized currently
4) Format Code block Dialog box, this dialog box cannot be re sized currently
5) Insert Symbol dialog box, this dialog box cannot be re sized currently

--> References tab
1) Manage Sources 
2) Insert Caption
3) Cross reference

--> Review tab
1) Spell check dialog box
2) Protect document

As shown in the attached screen shot when as spell checking dialog is opened , "Close button is not seen on the form even though it is present. Spell checking dialog box needs to be re sized.

When you open the color dialog, "Add custom color", "Ok" and "Cancel" buttons are not completely visible. Currently the dialog box can't be re-sized making it hard for the user to use as the button names are not visible so the user can't be sure what is being clicked. See the attached fig.

Can't see undo and redo button on the editor.

Steps:
1) Launch the RichTextEditor
2) Clear the existing contents or open a new file (using File-> New)
3) Insert a table of any dimensions for ex: 2x2
4) Delete the above added table
5) Now try to insert a new table of any dimensions (For ex: 2x2)
6) You will get the following exception when you run the project using vs2010
Index was out of range. Must be non-negative and less than the size of the collection.
Parameter name: index
7) In the demo application , you will see a Form1 error pop up opens up and makes the RichTextEditor completely blank

Steps:
1) Launch The RichTextEditor
2) Clear all the existing content
3) Type some text for ex: zzzz
4) Select the whole text and try to hit the backspace 
5) The typed text is not cleared and even you keep hitting the backspace the text is not cleared sometimes, it just stays

To reproduce:
- Import an html text snippet several times (the text should exceed one page)
- Select the entire text and bold it.
- Now make the text Italic
- You will notice that the text is not bold anymore.
 

To reproduce:

Open TelerikEditor and underline the whole text. Go to the end of a line and hold space. You will notice that the empty spaces are being underlined. The behavior is not the same as in Word.

Workaround:

Remove the underlining of the empty spaces at the end of the lines:

void Button_Click(object sender, EventArgs e)
{
    var caret = this.richTextBox.Document.CaretPosition;
    var originalPosition = new DocumentPosition(caret);
    caret.MoveToFirstPositionInDocument();
    do
    {
        caret.MoveToCurrentLineEnd();
        var endPos = new DocumentPosition(caret);

        caret.MoveToCurrentWordStart();
        caret.MoveToCurrentWordEnd();

        var startPos = new DocumentPosition(caret);

        this.richTextBox.Document.Selection.AddSelectionStart(startPos);
        this.richTextBox.Document.Selection.AddSelectionEnd(endPos);
        this.richTextBox.ChangeUnderlineDecoration(UnderlineType.None);
        this.richTextBox.Document.Selection.Clear();

        caret.MoveToCurrentLineEnd();

    }
    while (caret.MoveToNext());

    caret.MoveToPosition(originalPosition);
}

Beware that this workaround will not work in all cases. It should be used only prior to exporting or similar cases

To reproduce:
string text = "<p style=\"font-family:Calibri; font-size:15pt;\">Hi,<br/><br/><br/><br/>Regards<br/></p>";

HtmlFormatProvider provider = new HtmlFormatProvider();
RadDocument document = new RadDocument();
document = provider.Import(text);

radRichTextBox1.Document = document;

Click on an empty line and you will see that the font is different.

RadRichTextBox large txt documents (20000 rows)are loaded very slowly.

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: 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.

To reproduce:
- Insert the following HTML vide the HtmlFormatProvider: "<!DOCTYPE html><html><head><title>test</title> <body><span >Hello,</span><p ><span >Kind regards,</span></p> <br /> <span >Test</span><p><a href=\"#\"><span>Hyperlink</span></a><span ><br /></span><span >test: 0</span><span ><br /></span><span>Test</span><span  </span></p></body></html>"

- Start the application place the caret in front of the link and press the tab key, you will notice that the text below the link is also moved.

This behavior is also observed when the text box contains plain text or a imported rtf, just move the caret at the top left corner, in front of all text and press Tab. 

To reproduce:
- Import the following string using the HtmlFormatProvider:
 "<html><head>\r\n<meta http-equiv=\"Content-Type\" content=\"text/html; charset=utf-8\">\r\n  </head>\r\n  <body text=\"#000000\" bgcolor=\"#FFFFFF\">\r\n    Hej\r\n\r\n      <title>Sv: Tekniska </title>\r\n      \r\n\r\n    <br>\r\n    <pre>-- \r\nMvh Anders\r\n<a class=\"moz-txt-link-abbreviated\" href=\"http://www.abc.se\">www.abc.se</a></pre>\r\n  </body>\r\n</html>"

Workaround:
- Put a space or between the </a> and </pre> tags.

To reproduce:
Format a document with tables in MSWord. For example Insert a picture to the left and a table to the right. Import the document into RadRichTextBox. You will see that the formatting is not the same.

To reproduce:
- Paste some text with a barcode font in a RadRichTextBox.
- Export to a pdf document.
- In the pdf document the text is not displayed as barcode.

When importing HTML files if the font from the style contains serif element the font does not get interpreted correctly. For example "font-family: 'Times New Roman','serif';" - this will not work, but this font-family: 'Times New Roman';" will work.

RadRichTextBox - add import from PDF file.

If you import a rtf document, it produces a span instances with highlight color property set to ARGB(255,0,0,0).

Workaround:

foreach (Span span in document.EnumerateChildrenOfType<Span>())
{
    if (span.HighlightColor == Color.FromArgb(255, 0, 0, 0))
    {
        span.HighlightColor = Color.Transparent;
    }
}