Spell check does not refresh correctly when there are annotation markers around the current word.

As shown in the attached video.

Btw, I was using the MS Pinyin IME.

Working with PasteOptionsPopup may cause an exception in LayoutElement.SetParent. Very difficult to reproduce, having no consistent steps. Maybe it is related to undo of paste command, but there are no other clues aside from this.

Numbered lists have invalid values when combining documents by using the InsertFragment method.

Workaround: use RadDocumentMerger:

RadDocument radDocument1 = RtfSourceProvider.Import(rtf1);
RadDocument radDocument2 = RtfSourceProvider.Import(rtf2);

AppendDocumentOptions options = new AppendDocumentOptions();
options.FirstSourceSectionPropertiesResolutionMode = SectionPropertiesResolutionMode.NoSectionBreak;

RadDocumentMerger merger = new RadDocumentMerger(radDocument1);
merger.AppendDocument(radDocument2, options);

RichText.Document = merger.Document;

I have no idea how to reproduce this, but every so often after a paste operation into a RadRichTextBox, the host thread becomes unresponsive to user input. The message pump is still running but the following unhandled exception gets thrown in a tight infinite loop. The only way to close the window is to right click on the taskbar button.

System.NullReferenceException
Message: Object reference not set to an instance of an object.
Call Stack:
    at Telerik.Windows.Documents.Layout.LayoutElement.SetParent(LayoutElement newParent)
    at Telerik.Windows.Documents.Layout.LayoutBox.EnsureParent()
    at Telerik.Windows.Documents.Layout.LayoutBox.get_Parent()
    at Telerik.Windows.Documents.Layout.FormattingSymbolLayoutBox.get_IsEndOfCell()
    at Telerik.Windows.Documents.Layout.FormattingSymbolLayoutBox.GetFormattingSymbolVisual()
    at Telerik.Windows.Documents.SpanBoxPositionHandler.get_Location()
    at Telerik.Windows.Documents.UI.DocumentWebLayoutPresenter.GetViewPointFromDocumentPosition(DocumentPosition position)
    at Telerik.Windows.Controls.RichTextBoxUI.PasteOptionsPopup.CalculateLocation()
    at Telerik.Windows.Controls.RichTextBoxUI.PasteOptionsPopup.OnOwnerLayoutUpdated(Object sender, EventArgs e)
    at System.Windows.ContextLayoutManager.fireLayoutUpdateEvent()
    at System.Windows.ContextLayoutManager.UpdateLayout()
    at System.Windows.ContextLayoutManager.UpdateLayoutCallback(Object arg)
    at System.Windows.Media.MediaContext.FireInvokeOnRenderCallbacks()
    at System.Windows.Media.MediaContext.RenderMessageHandlerCore(Object resizedCompositionTarget)
    at System.Windows.Media.MediaContext.RenderMessageHandler(Object resizedCompositionTarget)
    at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
    at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Int32 numArgs, Delegate catchHandler)