Provide button functionality for the group dialog launcher.
Inheritance: LeftUpButtonController, ISourceController, IKeyController, IRibbonKeyTipTarget
        /// <summary>
        /// Initialize a new instance of the ViewDrawRibbonGroupDialogButton class.
        /// </summary>
        /// <param name="ribbon">Reference to owning ribbon control.</param>
        /// <param name="ribbonGroup">Reference to ribbon group this represents.</param>
        /// <param name="needPaint">Delegate for notifying paint requests.</param>
        public ViewDrawRibbonGroupDialogButton(KryptonRibbon ribbon,
                                               KryptonRibbonGroup ribbonGroup,
                                               NeedPaintHandler needPaint)
        {
            Debug.Assert(ribbon != null);
            Debug.Assert(ribbonGroup != null);

            // Remember incoming references
            _ribbon = ribbon;
            _ribbonGroup = ribbonGroup;

            // Attach a controller to this element for the pressing of the button
            DialogLauncherButtonController controller = new DialogLauncherButtonController(ribbon, this, needPaint);
            controller.Click += new MouseEventHandler(OnClick);
            MouseController = controller;
            SourceController = controller;
            KeyController = controller;
        }
        /// <summary>
        /// Initialize a new instance of the ViewDrawRibbonGroupDialogButton class.
        /// </summary>
        /// <param name="ribbon">Reference to owning ribbon control.</param>
        /// <param name="ribbonGroup">Reference to ribbon group this represents.</param>
        /// <param name="needPaint">Delegate for notifying paint requests.</param>
        public ViewDrawRibbonGroupDialogButton(KryptonRibbon ribbon,
                                               KryptonRibbonGroup ribbonGroup,
                                               NeedPaintHandler needPaint)
        {
            Debug.Assert(ribbon != null);
            Debug.Assert(ribbonGroup != null);

            // Remember incoming references
            _ribbon      = ribbon;
            _ribbonGroup = ribbonGroup;

            // Attach a controller to this element for the pressing of the button
            DialogLauncherButtonController controller = new DialogLauncherButtonController(ribbon, this, needPaint);

            controller.Click += new MouseEventHandler(OnClick);
            MouseController   = controller;
            SourceController  = controller;
            KeyController     = controller;
        }