[Python] Tkinter: Check if root has been destroyed?

I am writing an application using Tkinter along with threading.

The problem I got is, after closing the main app, some thread is still running, and I need a way to check whether the root windows has been destroyed to avoid the TclError: can't invoke "wm" command.

All methods I know: wminfo_exists() and state() all return error once the root is destroyed.

Continue reading...