Workaround:

private void radRichTextEditor1_CommentShowing(object sender, Telerik.WinForms.Documents.UI.CommentShowingEventArgs e)
{
  ((SelectionMiniToolBar)  this.radRichTextEditor1.RichTextBoxElement.SelectionMiniToolBar).Shown+=Form1_Shown;    
}
 
private void Form1_Shown(object sender, EventArgs e)
{
    ((SelectionMiniToolBar)sender).Visible = false;
    ((SelectionMiniToolBar)sender).VisibleChanged+=Form1_VisibleChanged;
}
 
private void Form1_VisibleChanged(object sender, EventArgs e)
{
    ((SelectionMiniToolBar)sender).Visible = false; 
}

Workaround: specify the users' dictionary with colors when the user is changed.
 
private void radRichTextEditor1_UserInfoChanged(object sender, EventArgs e)
{
    FieldInfo fi = typeof(TrackChangesOptions).GetField("userToColorMap", BindingFlags.Instance | BindingFlags.NonPublic) ;
    Dictionary<string, Telerik.WinControls.RichTextEditor.UI.Color> userToColorMap = fi.GetValue(radRichTextEditor1.RichTextBoxElement.TrackChangesOptions)
        as Dictionary<string, Telerik.WinControls.RichTextEditor.UI.Color>;
    userToColorMap = new Dictionary<string, Telerik.WinControls.RichTextEditor.UI.Color>();
    userToColorMap.Add("Boby1", Telerik.WinControls.RichTextEditor.UI.Color.FromRgb(0, 255, 255));
    userToColorMap.Add("Boby2", Telerik.WinControls.RichTextEditor.UI.Color.FromRgb(255, 0, 255));
    fi.SetValue(radRichTextEditor1.RichTextBoxElement.TrackChangesOptions, userToColorMap);
}

Add similar functionality as MS Word.

Whed the form is resized at some point the text of the items is not visible and there is a lot of free space.

When the border thickness is increased the table size should be increased as well - like in Microsoft Word.

RadRichTextBox - add import from PDF file.

Improve redo-undo functionality of RadRichTextBox to allow removing a whole sentence or word by pressing CTRL+Z

Html export of RadRichTextBox to perform font-size export in different units.

Case 2:
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);

ADD. RadRichTextBox - add support for auto capitalization

Support for opening word templates in RadRichTextBox

IMPROVE. RadRichTextBox - should be able to run with .NET Framework 3.5, rather than 4.0

RadRichTextBoxElement to be a custom editor of RadGridView

ADD. Export of Office 2010 dotx document templates.

ADD. RadRichTextBox - import text boxes from docx files

Currently it is not possible to control the HTML exported from RadRichTextBox and strip styles or embed them.

Currently this product cannot read the text contained in RichTextBox.