Add support for lower-alpha and upper-alpha.

When RadRichTextBox (in Paged layout mode) is in RadTabItem in RadTabControl, ribbon UI buttons and keyboard bindings are not working.

Workaround: Use System's TabControl instead of the RadTabControl.

Workaround: Manipulate the clipboard content in CommandExecuting even handler:

private void RichTextBox_CommandExecuting(object sender, Telerik.Windows.Documents.RichTextBoxCommands.CommandExecutingEventArgs e)
{
    if (e.Command is PasteCommand)
    {
        DocumentFragment document = ClipboardEx.GetDocument();
        bool hasChangedDocument = false;

        foreach (FieldRangeStart fieldStart in document.EnumerateChildrenOfType<FieldRangeStart>())
        {
            foreach (Span span in fieldStart.Field.GetFragmentByDisplayMode(FieldDisplayMode.Code).EnumerateChildrenOfType<Span>())
            {
                span.ForeColor = Colors.Black;
                hasChangedDocument = true;
            }
        }

        if (hasChangedDocument)
        {
            ClipboardEx.SetDocument(document);
        }
    }
}

If there is a paragraph with set background color, the styles for paragraphs are not reset after the colored one and this results in additional background color when importing RTF documents.

When a paragraph is styled in HTML format  with line-height it should be with AtLeast line spacing type instead of Exact. 

The same thing happens when the line-height is specified as normal: style="line-height: normal;". 

When trying to export a document which contains hyperlink pasted from Outlook, KeyNotFoundException is thrown. The color of the span is not registered.

To work around this, register a style with the same color:

StyleDefinition style = new StyleDefinition("test", StyleType.Character);
style.SpanProperties.ForeColor = Color.FromArgb(100, 200, 25, 104);
this.radRichTextBox.Document.StyleRepository.Add(style);

The TableStylesGallery keeps a reference to the document, which doesn't allow the GC to collect it. The issue is reproducible when the document is loaded in RadRichTextBox in the constructor of the window or in its Loaded event.

When the specified length of the stream is larger than the actual one, Adobe throws errors and removes the image.

Workaround:

Set the format provider settings:

PdfFormatProvider provider = new PdfFormatProvider();
PdfExportSettings exportSettings = new PdfExportSettings();
exportSettings.ContentsDeflaterCompressionLevel = 9;
exportSettings.ImagesDeflaterCompressionLevel = 9;
provider.ExportSettings = exportSettings;

As a result, table is visualized in RadRichTextBox with extremely large column widths.

The label for Decimal alignment is truncated.

The theme color is with higher priority. Thus, when the document is exported to DOCX and opened again, the default color is applied to the style.

The invalid document can't be measured and IndexOutOfRangeException/NullReferenceException will be thrown.

I have tried to use the RichTextBox, but found that it does not work very well when it comes to measure the text. This results in clipped text and that the caret can be displayed in a different place then expected.
This can easily be seen with a font like Gabriola, which uses complex kerning metrics. Type a text with a lot of "ff" and "fi" and you will soon see that your caret gets out of sync and that text is sometimes clipped.
When I look at the code of RichTextBox it seems to me that it uses its own calculation of text widths and that the this is based on a very simple method using just the kerning information. There is also a hard coded list containing information which fonts that has kerning info and which fonts that are mono spaced. It seems strange to me to have this in a config file since there is a large number of fonts used by the users.
It also seem to look at the Unicode character family in order to determine if ligatures are used or not, which is also quite strange since ligatures can be used for western characters too. The font Gabriola is an example of this. Look at "fi" in a word like "fine".
It can potentially consume a lot of memory since I think that it builds a dictionary of the kerning of all pairs of characters for all fonts that it encounters.
I guess this way of doing things were made for performance, but unfortunately, good performance doesn't help much if it doesn't work.
I am not sure if I should report this as a bug, since it is more of a fatal design issue of the whole control.

please add shapes support for radrichtextbox. else support another textbox