Private Sub RichTextBox1_TextChanged(ByVal sender As System.Object, ByVal e _
      As System.Windows.Controls.TextChangedEventArgs) Handles _
      RichTextBox1.TextChanged
 
        For Each change In e.Changes
            Label2.Content = change.Offset
 
            Dim RTB2 As TextPointer = _
              RichTextBox2.Document.ContentStart.GetPositionAtOffset( _
              change.Offset, LogicalDirection.Forward)
 
            If change.AddedLength >= 0 Then
                Dim Pointer = RichTextBox1.Document.ContentStart
                Dim ParagraphText As New TextRange(Pointer.GetPositionAtOffset( _
                  change.Offset, LogicalDirection.Forward), _
                  Pointer.GetPositionAtOffset(change.Offset + _
                  change.AddedLength, LogicalDirection.Forward))
 
                RTB2.InsertTextInRun(ParagraphText.Text)
                Label1.Content = ParagraphText.Text
            End If
 
            If change.RemovedLength >= 0 Then
                RTB2.DeleteTextInRun(change.RemovedLength)
            End If
 
        Next
    End Sub