Background process running when Unity Editor window is deactivated

I’m trying to communicate with my Unity plugin during Update() / LateUpdate() of my MonoBehavior script, even when Unity Editor or game is running in the background.

However, I found that if Unity Editor or game remains in the background, the Update() method family will never be called, including the EditorApplication.update delegates. Am I missing something like a flag to change this behavior or is this by design?

Note that this request is different from those that require EditorApplication.update and InitializeOnLoad attribute, where people need the callback when the Editor is in the foreground.

Thanks!