EditorWindow.Update without Unity having focus

Is there any way to repaint a custom editor (periodically) even when the application has no focus?

The EditorWindow.Update works when the Unity application has focus (Unity editor itself, not my custom editor window). But when I focus on another application (Notepad or Chrome, for example), the Update method stops working.

You could try using the update event in the EditorApplication class. If that doesn’t work i doubt that there is a way, at least not with built-in features.