The new functionality should allow the developer to load custom fonts in the memory and then use them in RadRichTextEditor.

Add support for shapes, and especially for shapes with textual content. 
In OOXML, shapes are represented by the wps:wsp element, and shapes with textual content by <wps:txbx>, <w:txbxContent>.
Such shape can be added to a Word document using the Insert -> Text -> Text Box -> Draw Text Box, or through a shape's context menu -> Add Text.

Note: Do not confuse with Text/Rich Text content controls (http://feedback.telerik.com/Project/154/Feedback/Details/156478 )

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.

When the caret position is inside Table and a page break is inserted, the table should be split into two tables with a page break between.

Support for math type equations. 

The scenario is very common, as in MS Word the option Table -> Layout -> Cell Size -> AutoFit ->  "AutoFit Contents" changes the PreferredWidth of the table and its columns to Auto.
Also the tables imported from HTML have these properties set by default.

Scenarios:
- Auto-sized table occupies minimal space.
- All auto-sized columns in a table (table itself could be, or could be not, auto-sized) should always be sized proportionally to their content length. Currently, such columns are sized equally in the case when there is enough space for all of the content, which is unexpected. (also see the attached images for the scenario with fixed-width table + auto-sized columns).

If I drag&drop a RadRichTextEditor i want a wizard like the RichTextBox-WPF-Control. I don't like the ribbon style, because I need a compact editor. So I like the CommandBarStrip look of the "command bar ui"-demo or the ASP.NET Editor.

Workaround: 

private void radRichTextEditor1_CommentShowing(object sender, Telerik.WinForms.Documents.UI.CommentShowingEventArgs e)
{
    this.radRichTextEditor1.RichTextBoxElement.ContextMenu.Opened-=ContextMenu_Opened;
    this.radRichTextEditor1.RichTextBoxElement.ContextMenu.Opened+=ContextMenu_Opened;
     
}
 
private void ContextMenu_Opened(object sender, Telerik.WinForms.Documents.UI.Extensibility.ContextMenuPlacementEventArgs e)
{
    this.radRichTextEditor1.RichTextBoxElement.ContextMenu.Hide();
}

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