Fix a rare deadlock in watchdog termination, inability to force quit/…

…restart NVDA if it freezes during exit and another rare watchdog edge case.

See the code comments and/or the ticket for full details.
Fixes #5189.

source/core.py

@@ -371,7 +371,6 @@ def Notify(self):
 	app.MainLoop()
 
 	log.info("Exiting")
-	messageWindow.destroy()
 	if updateCheck:
 		_terminate(updateCheck)
 
@@ -413,6 +412,9 @@ def Notify(self):
 			nvwave.playWaveFile("waves\\exit.wav",async=False)
 		except:
 			pass
+	# #5189: Destroy the message window as late as possible
+	# so new instances of NVDA can find this one even if it freezes during exit.
+	messageWindow.destroy()
 	log.debug("core done")
 
 def _terminate(module, name=None):

source/watchdog.py

@@ -64,10 +64,16 @@ def alive():
 def asleep():
 	"""Inform the watchdog that the core is going to sleep.
 	"""
+	# #5189: Reset in case the core was treated as dead.
+	alive()
+	# CancelWaitableTimer does not reset the signaled state; if it was signaled, it remains signaled.
+	# However, alive() calls SetWaitableTimer, which resets the timer to unsignaled.
 	windll.kernel32.CancelWaitableTimer(_coreDeadTimer)
 
 def _isAlive():
-	return winKernel.waitForSingleObject(_coreDeadTimer, 0) != 0
+	# #5189: If the watchdog has been terminated, treat the core as being alive.
+	# This will stop recovery if it has started and allow the watcher to terminate.
+	return not isRunning or winKernel.waitForSingleObject(_coreDeadTimer, 0) != 0
 
 def _watcher():
 	global isAttemptingRecovery