Is there a way to know when another hwnd has closed?

Question

Is there a method for setting up a listener/watcher to know when an unrelated application window is closed?

I can check to see if the window is still open, but that seems silly to continually do.

Answer 1

The Accessibility API's SetWinEventHook filtering for EVENT_OBJECT_DESTROY.

This is notification based so no polling and unlike a CBT hook does not require injection.