The border of the ContentControl is displayed abnormally when the paragraph's TextAlignment is set to Center or Right.

NullReferenceException is thrown when the "var" CSS function is used in the HTML on HtmlFormatProvider Import method call. 

The exception occurs only for CSS properties processed by RadRichTextBox. For example: "vertical-align", "font-family", "font-weight", "text-decoration-underline", etc.

The following HTML produces such error:

<span style="vertical-align: var(--my-variable);">
</span>

If the span tag doesn't have any content, the error doesn't occur.

The exception stacktrace is:

at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.FillSpanProperties(SpanProperties spanProps, EvaluateProperty evalFunction, IEnumerable`1 disregarderdDefaultStyleBagPropertiesCollection)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.CreateSpanFromTextNode(INode childNode, Paragraph paragraph, IEnumerable`1 disregarderdDefaultStyleBagPropertiesCollection)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessContentNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessHyperlinkNode(INode node, Action innerAction)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessAnnotationsForNode(INode node, Action innerAction)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessGenericNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.<>c__DisplayClass80_0.<ProcessNode>b__0()
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.ProcessNode(INode node)
   at Telerik.Windows.Documents.FormatProviders.Html.Import.HtmlDocumentImporter.Import(Stream input)

To work this around, avoid  using the "var" function in the CSS.

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

For now, We can drag or paste Images into RadRichTextBox. But still can't drag or paste files like RichTextBox in Winform. It's very inconvenient！

Please look for the same topic in the forum for context. 
@Todor:
Am attaching the wmf file and png file that don't get rendered.

Open a docx file in richtextbox, if numpages in headers do any subtraction, it can not display correctly. see the attached pictures for how to display in richtextbox and microsoft word 2016.

When word contains non-letters symbols at its start and/or end, it's always considered incorrect by the spell checker, even when it's present in the spell checking dictionary. The most common case is with abbreviations like "dr.", which should be invalid when are typed without the period ("dr"), but valid otherwise ("dr.")

Partial workaround: add the word without the punctuation to the dictionary. The problem is that the word without the punctuation will also be considered correct.

NullReferenceException is thrown when some of the parts in the template of SelectionMiniToolBar are missing, e.g. bold button, italic button, etc.; and selected text properties are changed while the selection mini tool bar is still opened, for example by clicking buttons in the ribbon UI.

Available in LIB Version 2017.3.1225.

NullReferenceException is thrown when documents are exported to PDF using PdfFormatProvider in multiple threads.

Available in R1 2018 Official Release Version.