SyntaxEditor Custom TextHighlightTag

public RadForm1()
{
    InitializeComponent();

    TextFormatDefinition def = new TextFormatDefinition(null,
                               new SolidBrush(System.Drawing.Color.Fuchsia),
                               null,
                               new Telerik.WinForms.Controls.SyntaxEditor.UI.Pen(new SolidBrush(System.Drawing.Color.Aqua), 1));
    this.radSyntaxEditor1.SyntaxEditorElement.TextFormatDefinitions.Remove("SelectedWordFormatDefinition");
    this.radSyntaxEditor1.SyntaxEditorElement.TextFormatDefinitions.AddLast(TextSearchHighlightTagger.SelectedWordFormatDefinition.Name, def);


    this.radSyntaxEditor1.SyntaxEditorElement.UILayersBuilder = new CustomUILayersBuilder();
    this.radSyntaxEditor1.TextFormatDefinitions.AddLast(MyTextSearchHighlightTagger.TelerikClassificationType,
    new TextFormatDefinition(new SolidBrush(System.Drawing.Color.Black), new SolidBrush(System.Drawing.Color.Red),
                         null,
                         new Telerik.WinForms.Controls.SyntaxEditor.UI.Pen(new SolidBrush(System.Drawing.Color.Green), 2)));

    MyTextSearchHighlightTagger highlightTagger = new MyTextSearchHighlightTagger(this.radSyntaxEditor1.SyntaxEditorElement);
    this.radSyntaxEditor1.TaggersRegistry.RegisterTagger(highlightTagger);
}
public class MyTextSearchHighlightTagger : WordTaggerBase
{
    public static readonly ClassificationType TelerikClassificationType = new ClassificationType("Telerik");
    public static readonly Dictionary<string, ClassificationType> WordsToClassificationType = new Dictionary<string, ClassificationType>();
    private StringComparison comparison = StringComparison.OrdinalIgnoreCase; 
    public MyTextSearchHighlightTagger(RadSyntaxEditorElement editor)
       : base(editor)
    { 
        WordsToClassificationType.Add("this", TelerikClassificationType);
        WordsToClassificationType.Add("editor", TelerikClassificationType);
    }

    protected override Dictionary<string, ClassificationType> GetWordsToClassificationTypes()
    {
        return MyTextSearchHighlightTagger.WordsToClassificationType;
    }

    public override IEnumerable<TagSpan<ClassificationTag>> GetTags(NormalizedSnapshotSpanCollection spans)
    {

        if (WordsToClassificationType.Count == 0)
        {
            yield break;
        }

        TextSnapshot snapshot = this.Document.CurrentSnapshot;
        foreach (TextSnapshotSpan snapshotSpan in spans)
        {
            string lineString = snapshotSpan.GetText();
            foreach (KeyValuePair<string, ClassificationType> searchWord in WordsToClassificationType)
            {

                int index = lineString.IndexOf(searchWord.Key, comparison);
                while (index != -1)
                {
                    TextSnapshotSpan tempSnapshotSpan = new TextSnapshotSpan(snapshot,
                        new Telerik.WinForms.SyntaxEditor.Core.Text.Span(snapshotSpan.Start + index, searchWord.Key.Length));

                    yield return new TagSpan<ClassificationTag>(tempSnapshotSpan, new ClassificationTag(TelerikClassificationType));

                    index = lineString.IndexOf(searchWord.Key, index + searchWord.Key.Length);
                }
            }
        }
    }
}

public class CustomUILayersBuilder : Telerik.WinForms.Controls.SyntaxEditor.UI.Layers.UILayersBuilder
{
    public override void BuildUILayers(UILayerStack uiLayers)
    { 
        uiLayers.AddLast(new MyTextUnderlineUILayer());
        base.BuildUILayers(uiLayers);
       
    }
}
public class MyTextUnderlineUILayer : LineBasedUILayer<ClassificationTag>
{
    public override string Name => "MyTextUnderlineUILayer";

    protected override FrameworkElement GetLinePartUIElement(ClassificationTag tag,
                                                             Telerik.WinForms.SyntaxEditor.Core.Text.Span span,
                                                             UIUpdateContext updateContext)
    {
        if (tag.ClassificationType != MyTextSearchHighlightTagger.TelerikClassificationType)
        {
            return null;
        }

        TextFormatDefinition textFormatting = updateContext.Editor.TextFormatDefinitions.
            GetTextFormatDefinition(MyTextSearchHighlightTagger.TelerikClassificationType);
        Telerik.WinControls.SyntaxEditor.UI.Rect rect = updateContext.Editor.GetLinePartBoundingRectangle(span, true);


        Telerik.WinControls.SyntaxEditor.UI.Rectangle rectangle = this.GetElementFromPool<Telerik.WinControls.SyntaxEditor.UI.Rectangle>();
        rectangle.Width = rect.Width;
        rectangle.Height = rect.Height;
        rectangle.Fill = textFormatting.Background;

        rectangle.Stroke = textFormatting.Border.Brush;
        rectangle.StrokeThickness = textFormatting.Border.Thickness.Left;

        return rectangle;
    }

    protected override void ResetPooledElementProperties(object element)
    {
    }
}

private void radTextBox1_TextChanged(object sender, EventArgs e)
{
    this.radSyntaxEditor1.SyntaxEditorElement.HighlightAllMatches(this.radTextBox1.Text);
}