Hi Janette,

In the absence of a property such as ButtonsRight collection on the piece you want to augment you can always use a CreationFilter to add the pieces you want to include.  Make a CreationFilter that adds a ButtonUIElement to the GroupBoxHeaderUIElement and positions itself accordingly. 

You can read more about CreationFilters here: http://help.infragistics.com/NetAdvantage/WinForms/2011.2/CLR2.0/?page=Win_Creation_Filter.html.

Some pseudocode to get you started if this is new:

        public void AfterCreateChildElements(Infragistics.Win.UIElement parent)
        {
            if (parent is Infragistics.Win.Misc.GroupBoxHeaderUIElement)
            {
                Infragistics.Win.Misc.GroupBoxHeaderUIElement header =
                    (Infragistics.Win.Misc.GroupBoxHeaderUIElement) parent;
                Infragistics.Win.ButtonUIElement button = new ButtonUIElement(parent);
                Rectangle parentRect = parent.RectInsideBorders;
                button.Rect = new Rectangle(parentRect.X + parentRect.Width - 20, parentRect.Y, 20, 20);
                button.Text = "C";
                button.ElementClick += new UIElementEventHandler(button_ElementClick);
                parent.ChildElements.Add(button);
            }
        }

        void button_ElementClick(object sender, UIElementEventArgs e)
        {
            MessageBox.Show("Button clicked");
        }

        public bool BeforeCreateChildElements(Infragistics.Win.UIElement parent)
        {
            return false;
        }