def _get_isAlive(self):
		if not winUser.isWindow(self.rootNVDAObject.windowHandle):
			return False
		try:
			self.rootNVDAObject.UIAElement.currentProviderDescription
		except COMError:
			return False
		return True

	def _get_isAlive(self):
		if not winUser.isWindow(self.rootNVDAObject.windowHandle):
			return False
		try:
			return self.rootNVDAObject.excelWorksheetObject.name==self.rootNVDAObject.excelApplicationObject.activeSheet.name
		except (COMError,AttributeError,NameError):
			log.debugWarning("could not compare sheet names",exc_info=True)
			return False

	def _get_isAlive(self):
		if self.isLoading:
			return True
		root=self.rootNVDAObject
		if not root:
			return False
		if not winUser.isWindow(root.windowHandle) or root.role == controlTypes.ROLE_UNKNOWN:
			return False
		return True

	def _get_isAlive(self):
		if self.isLoading:
			return True
		root=self.rootNVDAObject
		if not root:
			return False
		states=root.states
		if not winUser.isWindow(root.windowHandle) or controlTypes.STATE_DEFUNCT in states or controlTypes.STATE_READONLY not in states:
			return False
		return True

def winEventCallback(handle,eventID,window,objectID,childID,threadID,timestamp):
	try:
		#Ignore all object IDs from alert onwards (sound, nativeom etc) as we don't support them
		if objectID<=winUser.OBJID_ALERT: 
			return
		#Ignore all locationChange events except ones for the caret
		if eventID==winUser.EVENT_OBJECT_LOCATIONCHANGE and objectID!=winUser.OBJID_CARET:
			return
		if eventID==winUser.EVENT_OBJECT_DESTROY:
			processDestroyWinEvent(window,objectID,childID)
			return
		#Change window objIDs to client objIDs for better reporting of objects
		if (objectID==0) and (childID==0):
			objectID=winUser.OBJID_CLIENT
		#Ignore events with invalid window handles
		isWindow = winUser.isWindow(window) if window else 0
		if window==0 or (not isWindow and eventID in (winUser.EVENT_SYSTEM_SWITCHSTART,winUser.EVENT_SYSTEM_SWITCHEND,winUser.EVENT_SYSTEM_MENUEND,winUser.EVENT_SYSTEM_MENUPOPUPEND)):
			window=winUser.getDesktopWindow()
		elif not isWindow:
			return

		if childID<0:
			tempWindow=window
			while tempWindow and not winUser.getWindowStyle(tempWindow)&winUser.WS_POPUP and winUser.getClassName(tempWindow)=="MozillaWindowClass":
				tempWindow=winUser.getAncestor(tempWindow,winUser.GA_PARENT)
			if tempWindow and winUser.getClassName(tempWindow).startswith('Mozilla'):
				window=tempWindow

		windowClassName=winUser.getClassName(window)
		#At the moment we can't handle show, hide or reorder events on Mozilla Firefox Location bar,as there are just too many of them
		#Ignore show, hide and reorder on MozillaDropShadowWindowClass windows.
		if windowClassName.startswith('Mozilla') and eventID in (winUser.EVENT_OBJECT_SHOW,winUser.EVENT_OBJECT_HIDE,winUser.EVENT_OBJECT_REORDER) and childID<0:
			#Mozilla Gecko can sometimes fire win events on a catch-all window which isn't really the real window
			#Move up the ancestry to find the real mozilla Window and use that
			if winUser.getClassName(window)=='MozillaDropShadowWindowClass':
				return
		if eventID==winUser.EVENT_SYSTEM_FOREGROUND:
			#We never want to see foreground events for the Program Manager or Shell (task bar) 
			if windowClassName in ("Progman","Shell_TrayWnd"):
				return
			# #3831: Event handling can be deferred if Windows takes a while to change the foreground window.
			# See pumpAll for details.
			global _deferUntilForegroundWindow,_foregroundDefers
			_deferUntilForegroundWindow=window
			_foregroundDefers=0
		if windowClassName=="MSNHiddenWindowClass":
			# HACK: Events get fired by this window in Windows Live Messenger 2009 when it starts.
			# If we send a WM_NULL to this window at this point (which happens in accessibleObjectFromEvent), Messenger will silently exit (#677).
			# Therefore, completely ignore these events, which is useless to us anyway.
			return
		if winEventLimiter.addEvent(eventID,window,objectID,childID,threadID):
			core.requestPump()
	except:
		log.error("winEventCallback", exc_info=True)

	def _get_isAlive(self):
		if self.isLoading:
			return True
		root=self.rootNVDAObject
		if not root:
			return False
		if not winUser.isWindow(root.windowHandle) or controlTypes.STATE_DEFUNCT in root.states:
			return False
		try:
			if not NVDAObjects.IAccessible.getNVDAObjectFromEvent(root.windowHandle,winUser.OBJID_CLIENT,root.IA2UniqueID):
				return False
		except:
			return False
		return True

	def _get_isAlive(self):
		if self.isLoading:
			return True
		root=self.rootNVDAObject
		if not root:
			return False
		if not winUser.isWindow(root.windowHandle):
			return False
		try:
			isDefunct=bool(root.IAccessibleObject.states&IAccessibleHandler.IA2_STATE_DEFUNCT)
		except COMError:
			# If IAccessible2 states can not be fetched at all, defunct should be assumed as the object has clearly been disconnected or is dead
			isDefunct=True
		return not isDefunct

 def _get_isAlive(self):
     if self.isLoading:
         return True
     root = self.rootNVDAObject
     if not root:
         return False
     try:
         if not root.IAccessibleRole:
             # The root object is dead.
             return False
     except watchdog.CallCancelled:
         # #1831: If the root object isn't responding, treat the buffer as dead.
         # Otherwise, we'll keep querying it on every focus change and freezing.
         return False
     states = root.states
     if not winUser.isWindow(root.windowHandle) or controlTypes.STATE_EDITABLE in states:
         return False
     return True

def winEventToNVDAEvent(eventID,window,objectID,childID,useCache=True):
	"""Tries to convert a win event ID to an NVDA event name, and instanciate or fetch an NVDAObject for the win event parameters.
	@param eventID: the win event ID (type)
	@type eventID: integer
	@param window: the win event's window handle
	@type window: integer
	@param objectID: the win event's object ID
	@type objectID: integer
	@param childID: the win event's childID
	@type childID: the win event's childID
	@param useCache: C{True} to use the L{liveNVDAObjectTable} cache when retrieving an NVDAObject, C{False} if the cache should not be used.
	@type useCache: boolean
	@returns: the NVDA event name and the NVDAObject the event is for
	@rtype: tuple of string and L{NVDAObjects.IAccessible.IAccessible}
	"""
	NVDAEventName=winEventIDsToNVDAEventNames.get(eventID,None)
	if not NVDAEventName:
		return None
	#Ignore any events with invalid window handles
	if not window or not winUser.isWindow(window):
		return None
	#Make sure this window does not have a ghost window if possible
	if NVDAObjects.window.GhostWindowFromHungWindow and NVDAObjects.window.GhostWindowFromHungWindow(window):
		return None
	#We do not support MSAA object proxied from native UIA
	if UIAHandler.handler and UIAHandler.handler.isUIAWindow(window):
		return None
	obj=None
	if useCache:
		#See if we already know an object by this win event info
		obj=liveNVDAObjectTable.get((window,objectID,childID),None)
	#If we don't yet have the object, then actually instanciate it.
	if not obj: 
		obj=NVDAObjects.IAccessible.getNVDAObjectFromEvent(window,objectID,childID)
	#At this point if we don't have an object then we can't do any more
	if not obj:
		return None
	#SDM MSAA objects sometimes don't contain enough information to be useful
	#Sometimes there is a real window that does, so try to get the SDMChild property on the NVDAObject, and if successull use that as obj instead.
	if 'bosa_sdm' in obj.windowClassName:
		SDMChild=getattr(obj,'SDMChild',None)
		if SDMChild: obj=SDMChild
	return (NVDAEventName,obj)

def winEventToNVDAEvent(eventID,window,objectID,childID,useCache=True):
	"""Tries to convert a win event ID to an NVDA event name, and instanciate or fetch an NVDAObject for the win event parameters.
	@param eventID: the win event ID (type)
	@type eventID: integer
	@param window: the win event's window handle
	@type window: integer
	@param objectID: the win event's object ID
	@type objectID: integer
	@param childID: the win event's childID
	@type childID: the win event's childID
	@param useCache: C{True} to use the L{liveNVDAObjectTable} cache when retrieving an NVDAObject, C{False} if the cache should not be used.
	@type useCache: boolean
	@returns: the NVDA event name and the NVDAObject the event is for
	@rtype: tuple of string and L{NVDAObjects.IAccessible.IAccessible}
	"""
	#We can't handle MSAA create events. (Destroys are handled elsewhere.)
	if eventID == winUser.EVENT_OBJECT_CREATE:
		return None
	#Handle the special MSAA caret object's locationChange and show events as 'caret' events for the focus object
	NVDAEventName=winEventIDsToNVDAEventNames.get(eventID,None)
	if not NVDAEventName:
		return None
	#Ignore any events with invalid window handles
	if not window or not winUser.isWindow(window):
		return None
	obj=None
	if useCache:
		#See if we already know an object by this win event info
		obj=liveNVDAObjectTable.get((window,objectID,childID),None)
	#If we don't yet have the object, then actually instanciate it.
	if not obj: 
		obj=NVDAObjects.IAccessible.getNVDAObjectFromEvent(window,objectID,childID)
	#At this point if we don't have an object then we can't do any more
	if not obj:
		return None
	#SDM MSAA objects sometimes don't contain enough information to be useful
	#Sometimes there is a real window that does, so try to get the SDMChild property on the NVDAObject, and if successull use that as obj instead.
	if 'bosa_sdm' in obj.windowClassName:
		SDMChild=getattr(obj,'SDMChild',None)
		if SDMChild: obj=SDMChild
	return (NVDAEventName,obj)

	def _get_isAlive(self):
		if self.isLoading:
			return True
		root=self.rootNVDAObject
		if not root:
			return False
		if not winUser.isWindow(root.windowHandle):
			return False
		if not root.isInForeground:
			# #7818: Subsequent checks make COM calls.
			# The chances of a buffer dying while the window is in the background are
			# low, so don't make COM calls in this case; just treat it as alive.
			# This prevents freezes on every focus change if the browser process
			# stops responding; e.g. it froze, crashed or is being debugged.
			return True
		try:
			isDefunct=bool(root.IAccessibleObject.states&IAccessibleHandler.IA2_STATE_DEFUNCT)
		except COMError:
			# If IAccessible2 states can not be fetched at all, defunct should be assumed as the object has clearly been disconnected or is dead
			isDefunct=True
		return not isDefunct

	def _get_isAlive(self):
		if self.isLoading:
			return True
		root=self.rootNVDAObject
		if not root:
			return False
		if not winUser.isWindow(root.windowHandle):
			return False
		if root.appModule.appName.startswith('wwahost') and not winUser.isDescendantWindow(winUser.getForegroundWindow(),root.windowHandle):
			# #4572: When a wwahost hosted app is in the background it gets suspended and all COM calls freeze.
			# Therefore we don't have enough info to say whether its dead or not. We assume it is alive until we can get a better answer.
			return True
		try:
			if not root.IAccessibleRole:
				# The root object is dead.
				return False
		except watchdog.CallCancelled:
			# #1831: If the root object isn't responding, treat the buffer as dead.
			# Otherwise, we'll keep querying it on every focus change and freezing.
			return False
		states=root.states
		if controlTypes.STATE_EDITABLE in states:
			return False
		return True

	def _get_isAlive(self):
		root = self.rootNVDAObject
		return winUser.isWindow(root.windowHandle)

	def isAlive(self):
		return winUser.isWindow(self.rootNVDAObject.windowHandle)