How to reproduce:
public partial class Form1 : Form
{
    RadRichTextBox tb1;
    RadRichTextBox tb2;
    private bool shouldFocus = false;

    public Form1()
    {
        InitializeComponent();

        tb1 = new RadRichTextBox();
        this.Controls.Add(tb1);

        tb2 = new RadRichTextBox();
        tb2.Location = new Point(200, 0);
        this.Controls.Add(tb2);

        this.Load += Form1_Load;
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        StyleDefinition style = new StyleDefinition();
        tb1.IsReadOnly = true;
        tb1.Document.Insert("text 1", style);

        tb2.Document.Insert("text 2", style);
        tb2.IsReadOnly = true;
    }

    private void radButton1_Click(object sender, EventArgs e)
    {
        tb1.IsReadOnly = false;
        tb2.IsReadOnly = false;
        tb1.Focus();
    }
}

Workaround:
public partial class Form1 : Form
{
    RadRichTextBox tb1;
    RadRichTextBox tb2;
    private bool shouldFocus = false;

    public Form1()
    {
        InitializeComponent();

        tb1 = new RadRichTextBox();
        tb1.GotFocus += tb1_GotFocus;
        tb1.LostFocus += tb1_LostFocus;
        this.Controls.Add(tb1);

        tb2 = new RadRichTextBox();
        tb2.Location = new Point(200, 0);
        tb2.GotFocus += tb2_GotFocus;
        tb2.LostFocus += tb2_LostFocus;
        this.Controls.Add(tb2);

        this.Load += Form1_Load;
    }

    private void tb2_LostFocus(object sender, EventArgs e)
    {
        shouldFocus = false;
        tb2.IsReadOnly = true;
    }

    private void tb2_GotFocus(object sender, EventArgs e)
    {
        if (shouldFocus)
        {
            tb2.IsReadOnly = false;
        }
    }

    private void tb1_LostFocus(object sender, EventArgs e)
    {
        tb1.IsReadOnly = true;
    }

    private void tb1_GotFocus(object sender, EventArgs e)
    {
        if (shouldFocus)
        {
            tb1.IsReadOnly = false;
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {
        StyleDefinition style = new StyleDefinition();
        tb1.IsReadOnly = true;
        tb1.Document.Insert("text 1", style);

        tb2.Document.Insert("text 2", style);
        tb2.IsReadOnly = true;
    }

    private void radButton1_Click(object sender, EventArgs e)
    {
        if (shouldFocus)
        {
            tb2.Focus();
        }
        else
        {
            shouldFocus = true;
            tb1.Focus();
        }
    }
}

To reproduce:
- Add comment and try to select the text with the mouse.

Workaround: use keyboard to select the desired text

To reproduce:
- Create a document in Word and add image watermark to it.
- Open the document in RadRichtextEditor

Add similar functionality as MS Word.

To reproduce:
- Add some full pages to the editor. 
- Remove all margin from the print settings and document settings.
- PrintPreview the document.
- Seth the print preview dialog zoom to 100% and compare the documents.
- You will notice that the print document's content is smaller.

To reproduce: 
1. Create a UserControl.
2. Drag from the Toolbox a RichTextEditorRibbonBar and drop it onto the UserControl.
3. Use the following code:
Sub New()
    InitializeComponent()
    Me.RichTextEditorRibbonBar1.CloseButton = False
    Me.RichTextEditorRibbonBar1.MinimizeButton = False
    Me.RichTextEditorRibbonBar1.MaximizeButton = False
End Sub

You will notice that the header is cut off.

Workaround: in order to hide the system buttons, use the following code:

 Me.RichTextEditorRibbonBar1.RibbonBarElement.RibbonCaption.SystemButtons.Visibility = Telerik.WinControls.ElementVisibility.Hidden

To reproduce:

Import the attached sample.html in RadRichTextEditor. Afterwards, export the content by using HtmlFormatProvider. You will notice that the page breaks are not exported and if you import the exported file, you will see the difference. Please refer to the attached screenshot.

Whed the form is resized at some point the text of the items is not visible and there is a lot of free space.

To reproduce:
- Export rtf file with a bullet list - use the old RadRichTextBox.
- Import the file in the RadRichTextEditor in WebLayout mode.
- The entire list is shifted to the left and the bullets are not visible.

The issue is present because the old RadRichTextBox was exporting bullets with negative indent and the WebLayout mode always starts from 0.

To reproduce:
- Create new application with a richtextbox in it.
- Build it and merge the assemblies.
- Start the application type some text then select a part of it and try to do something else.
- Note that this occur only the first time when the application is started.

When the border thickness is increased the table size should be increased as well - like in Microsoft Word.

1) Launch the RadRichTextEditor
2) enter some text (at least three lines)
3) select the whole content and apply bullets/ numbers 
5) Since the whole content is already selected, open the font color dialog box and try to apply a color (say red color)
6) Notice for the last item in the list , the selected color is not applied to the bullets/ numbers as shown in the attached figs

To reproduce:
- Import an html text snippet several times (the text should exceed one page)
- Select the entire text and bold it.
- Now make the text Italic
- You will notice that the text is not bold anymore.
 

To reproduce:

Open TelerikEditor and underline the whole text. Go to the end of a line and hold space. You will notice that the empty spaces are being underlined. The behavior is not the same as in Word.

Workaround:

Remove the underlining of the empty spaces at the end of the lines:

void Button_Click(object sender, EventArgs e)
{
    var caret = this.richTextBox.Document.CaretPosition;
    var originalPosition = new DocumentPosition(caret);
    caret.MoveToFirstPositionInDocument();
    do
    {
        caret.MoveToCurrentLineEnd();
        var endPos = new DocumentPosition(caret);

        caret.MoveToCurrentWordStart();
        caret.MoveToCurrentWordEnd();

        var startPos = new DocumentPosition(caret);

        this.richTextBox.Document.Selection.AddSelectionStart(startPos);
        this.richTextBox.Document.Selection.AddSelectionEnd(endPos);
        this.richTextBox.ChangeUnderlineDecoration(UnderlineType.None);
        this.richTextBox.Document.Selection.Clear();

        caret.MoveToCurrentLineEnd();

    }
    while (caret.MoveToNext());

    caret.MoveToPosition(originalPosition);
}

Beware that this workaround will not work in all cases. It should be used only prior to exporting or similar cases

To reproduce:
string text = "<p style=\"font-family:Calibri; font-size:15pt;\">Hi,<br/><br/><br/><br/>Regards<br/></p>";

HtmlFormatProvider provider = new HtmlFormatProvider();
RadDocument document = new RadDocument();
document = provider.Import(text);

radRichTextBox1.Document = document;

Click on an empty line and you will see that the font is different.

RadRichTextBox large txt documents (20000 rows)are loaded very slowly.