public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            DockTileIndicator.ShowIndicator = true;
            DockTileIndicator.SetText(_number.ToString());

            ckb_showBadge.AllowsMixedState = false;
            ckb_showBadge.Activated       += (sender, e) => {
                if (ckb_showBadge.State == NSCellStateValue.On)
                {
                    DockTileIndicator.ShowIndicator = true;
                }

                else if (ckb_showBadge.State == NSCellStateValue.Off)
                {
                    DockTileIndicator.ShowIndicator = false;
                }
            };

            btn_addBadge.Activated += (sender, e) => {
                ++_number;
                DockTileIndicator.SetText(_number.ToString());
            };

            btn_clear.Activated += (sender, e) =>
                                   DockTileIndicator.SetText(null);


            //tray
            btn_showTray.Activated += (sender, e) => {
                var menu = new NSMenu();
                menu.AddItem(new NSMenuItem("MenuItem1"));
                menu.AddItem(new NSMenuItem("MenuItem2"));
                menu.AddItem(new NSMenuItem("MenuItem3"));

                _tray.CreateTray(menu);

                btn_showTray.Enabled = false;
                btn_hideTray.Enabled = true;
            };

            btn_hideTray.Activated += (sender, e) => {
                _tray.RemoveTray();

                btn_showTray.Enabled = true;
                btn_hideTray.Enabled = false;
            };

            btn_hideTray.Enabled = false;
        }