To reproduce: please refer to the attached gif file

Add a custom tab in the ribbon UI and a RadDropDownListElement bound to a list of strings. The first item is selected by default. Insert a table by using the ribbon UI and try to get programmatically the RadDropDownListElement.SelectedValue/Index. It is null/-1 although the text is correct.

Workaround:

public class CustomRichTextEditorRibbonBar : RichTextEditorRibbonBar
{
           protected override void CreateChildItems(RadElement parent)
    {
        base.CreateChildItems(parent);
        FieldInfo fi = typeof(RadRibbonBar).GetField("ribbonBarElement", BindingFlags.Instance | BindingFlags.NonPublic);
        RadRibbonBarElement ribbonBarElement = fi.GetValue(this) as RadRibbonBarElement;

        ribbonBarElement = new CustomRadRibbonBarElement();
        fi.SetValue(this, ribbonBarElement);
        this.RootElement.Children.Add(ribbonBarElement);

        ribbonBarElement.CommandTabSelecting +=
            delegate (object sender, CommandTabSelectingEventArgs args) { OnCommandTabSelecting(args); };
        ribbonBarElement.CommandTabSelected +=
            delegate (object sender, CommandTabEventArgs args) { OnCommandTabSelected(args); };

        ribbonBarElement.ExpandedStateChanged += delegate (object sender, EventArgs args)
        {
            this.OnRibbonBarExpandedStateChanged(args);
        };


    }
}

public class CustomRadRibbonBarElement : RadRibbonBarElement
{
  
    protected override float GetMaximumTabContentHeight()
    {
        return 104; 
    }
}

The attached video shows how you can reproduce this.

How to reproduce: check the attached video

Workaround: 
public partial class Form1 : Form
{
    private RadButtonElement buttonHeader;
    private RadButtonElement buttonFooter; 

    public Form1()
    {
        InitializeComponent();

        this.buttonHeader = (RadButtonElement)this.richTextEditorRibbonBar1.GetType().GetField("buttonHeader", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(this.richTextEditorRibbonBar1);
        this.buttonFooter = (RadButtonElement)this.richTextEditorRibbonBar1.GetType().GetField("buttonFooter", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(this.richTextEditorRibbonBar1);
        
        this.radRichTextEditor1.RichTextBoxElement.IsInHeaderFooterEditModeChanged += RichTextBoxElement_IsInHeaderFooterEditModeChanged;
    }
    
    private void RichTextBoxElement_IsInHeaderFooterEditModeChanged(object sender, EventArgs e)
    {
        if (!this.radRichTextEditor1.RichTextBoxElement.IsInHeaderFooterEditMode)
        {
            this.buttonHeader.Enabled = true;
            this.buttonFooter.Enabled = true;
        }
        else
        {
            this.buttonHeader.Enabled = false;
            this.buttonFooter.Enabled = false;
        }
    }
}

When exporting to HTML, each two consequent spaces in a run are treated as  . However, when a style is applied to one of the spaces, the span is split and the two spaces are not considered as a pair, therefore, the HtmlFormatProvider exports them as normal spaces.

When the two spaces are the whole content of a paragraph, this paragraph is not visible when the HTML is visualized in a browser. 

To reproduce:

1. Add a RichTextEditorRibbonBar on the form
2. Add a RadRichTextEditor on the form.
3. Set the RichTextEditorRibbonBar.AssociatedRichTextEditor property.
4. Run the application. You will notice that the caret for the RadRichTextEditor is displayed and the user expects to start entering text when pressing the keyboard. However,  the focused control in this case is the font family drop-down and it accepts the input. 

Workaround: focus the RadRichTextEditor in the Form.Shown event:

Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles MyBase.Shown
    Me.RadRichTextEditor1.Focus()
End Sub

To reproduce:
- Click the InsertMergeFiled button before setting the data source.
- Set the data source.
- Click the button again.
- There are no items in it.
 

Workaround:
Friend Class MyRichTextEditorRibbonBar
    Inherits RichTextEditorRibbonBar



    Protected Overrides Sub dropDownButtonInsertMergeField_DropDownOpening(sender As Object, e As CancelEventArgs)
        MyBase.dropDownButtonInsertMergeField_DropDownOpening(sender, e)
        If Me.dropDownButtonInsertMergeField.Items.Count = 0 Then
            Me.dropDownButtonInsertMergeField.Items.Add(New RadItem)
        End If
    End Sub

End Class

To reproduce:
- Set the layout to Paged.
- Add a table
- Switch the layout to Flow and try to resize it on the right most border.

Workaround:
Switch to paged layout and resize the table.

If we copy-paste some french text; f.e. generated by https://fr.lipsum.com/:

This is the original text:

"Le Lorem Ipsum est simplement du faux texte employé dans la composition et la mise en page avant impression. Le Lorem Ipsum est le faux texte standard de l'imprimerie depuis les années 1500"

This is what we see if we past it inside the rich text component

Le Lorem Ipsum est simplement du faux texte employé dans la composition et la mise en page avant impression. Le Lorem Ipsum est le faux texte standard de l'imprimerie depuis les années 1500

To reproduce: 
Please refer to the attached sample application and video demonstrating the experience issue. 

Workaround: 
Set RadRichTextEditor to null in Form`s Dispose method: 
Protected Overrides Sub Dispose(ByVal disposing As Boolean)
    Me.RadRichTextEditor1 = Nothing
    Try
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
    Finally
        MyBase.Dispose(disposing)
    End Try
End Sub

This field retrieves a character through a code value specified in the field-argument. Such documents are common and are created when symbols (e.g. with font Windings through Insert -> Symbol dialog) are inserted in RTF documents in MS Word.

Workaround: 
private void ClearDictionaries(RadRichTextEditor editor)
{
    var dictionaries = typeof(DocumentSpellChecker).GetField("dictionaries", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(editor.SpellChecker) as Dictionary<CultureInfo, Lazy<IWordDictionary>>;
    dictionaries.Clear();
    var customDictionaries = typeof(DocumentSpellChecker).GetField("customDictionaries", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(editor.SpellChecker) as Dictionary<CultureInfo, ICustomWordDictionary>;
    customDictionaries.Clear();
}

The RTF specifications states that the header of the document should start with "\rtfN" where N is the version of the RTF. Currently, the RtfFormatProvider do not save the version, but only "\rtf". Most software handles this case, but in some cases the document cannot be read.

To reproduce: 

• Add a table and select 3 rows.
• From the context menu select Delete Row
• Only one row is deleted

InvalidOperationException is thrown in the IsInNonEditableRange() method of RadDocument when assigning a document to RadRichTextBox, which is created through the model and contains several read-only ranges.

Workaround: Call MeasureAndArrangeInDefaulSize().

To reproduce: please refer to the attached sample project. You will notice that the exported HTML content from the left RadRichTextEditor is imported to the right and the bullets are not the same.