I have a third party WinForms control that I need to use for visualizing and saving data as images. I don’t really need to see the form on my screen, I just need it to exist. Currently I just create a new Thread, set it to STA and then create a Form on the thread (and move the form off the screen because I don’t want to see it). The thread then gets blocked in a loop where it sometimes picks up items for rendering from a BlockingCollection

According to this answer I should start a message loop using Application.Run(form) on this thread and I should also not block this thread. My code violates both of these principles.

Based on my limited testing I can’t see any issues with my approach but I lack the depth of understanding to foresee potential issues here.

private static void ProcessQueue()
{
    // This function gets passed in the Thread ctor

    Debug.Assert(Thread.CurrentThread.GetApartmentState() == ApartmentState.STA);

    var form = new Form()
    {
        ShowInTaskbar = false,
        Height = 800,
        Width = 800,
        FormBorderStyle = FormBorderStyle.None,
        MaximizeBox = false,
        MinimizeBox = false,
        Text = "Graphics helper window"
    };

    var display = new MyThirdPartyActiveXDisplay();
    form.Controls.Add(display);
    display.Dock = DockStyle.Fill;

    form.Show();

    form.Top = -2000;
    form.Left = -2000;

    while (!SaveQueue.IsCompleted)
    {
        var item = SaveQueue.Take();

        var image = display.render(item.value)

        item.SetResult(image); // This uses a TaskCompletionSource under the hood to pass the result to the caller that added the item to the queue
    }
}

What potential risks should I look for with this approach? Why is it recommended to start a message pump and not block an STAThread?