In my other methods I could do something like this,

    public void Add(T item)
    {
        if (dispatcher.CheckAccess())
        {
            ...
        }
        else
        {
            dispatcher.Invoke(new Action<T>(Add), item);
        }
    }

But how do I invoke a property for a situation like this?

    public T this[int index]
    {
        get
        {
            ...
        }
        set
        {
            if (dispatcher.CheckAccess())
            {
                ...
            }
            else
            {
                dispatcher.Invoke(???, index); // <-- problem is here
            }
        }
    }