private List<UIElement> _controlsList = new List<UIElement>();
_controlsList.Add(SetSelectControl());

private CommonControls.SelectRestoreFilesControl SetSelectControl()
        {
            var control = new CommonControls.SelectRestoreFilesControl();
            control.SelectRestoreFiles += SelectRestoreFiles;
            control.SelectRestoreFilesClose += SelectRestoreFilesClose;
            smallgrid.Children.Add(control);
            control.FilePopUp.IsOpen = false;
            return control;
        }

control.FilePopUp.IsOpen = false;

var control = _controlList.First() as Control;
Control.FilePopUp.IsOpen = true;