public virtual void Initialise(ItemsControl todoList, ObservableCollection<ToDoItemViewModel> todoItems)
{
_todoList = todoList;
_todoItems = todoItems;
// when the ItemsControl has been rendered, we can locate the ScrollViewer
// that is within its template.
_todoList.InvokeOnNextLayoutUpdated(() => LocateScrollViewer());
IsEnabled = true;
}
