https://learn.microsoft.com/pl-pl/dotnet/api/system.windows.threading.dispatcher.shutdownfinished?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-10.0
Dispatcher.ShutdownFinished Event (System.Windows.Threading) | Microsoft Learn
Occurs when the Dispatcher finishes shutting down.
event systemdispatcherwindowsthreadingmicrosoft