How to use the watchdog.cancellableSendMessage function in watchdog

def _getFormatFieldAndOffsets(self,offset,formatConfig,calculateOffsets=True):
		style=watchdog.cancellableSendMessage(self.obj.windowHandle,SCI_GETSTYLEAT,offset,0)
		if calculateOffsets:
			#we need to manually see how far the style goes, limit to line
			lineStart,lineEnd=self._getLineOffsets(offset)
			startOffset=offset
			while startOffset>lineStart:
				curStyle=watchdog.cancellableSendMessage(self.obj.windowHandle,SCI_GETSTYLEAT,startOffset-1,0)
				if curStyle==style:
					startOffset-=1
				else:
					break
			endOffset=offset+1
			while endOffset

def _get_parent(self):
		if self.IAccessibleChildID==0:
			return super(TreeViewItem,self)._get_parent()
		hItem=self.treeview_hItem
		if not hItem:
			return super(TreeViewItem,self)._get_parent()
		parentItem=watchdog.cancellableSendMessage(self.windowHandle,TVM_GETNEXTITEM,TVGN_PARENT,hItem)
		if parentItem<=0:
			return super(TreeViewItem,self)._get_parent()
		newID=watchdog.cancellableSendMessage(self.windowHandle,TVM_MAPHTREEITEMTOACCID,parentItem,0)
		if not newID:
			# Tree views from comctl < 6.0 use the hItem as the child ID.
			newID=parentItem
		return IAccessible(windowHandle=self.windowHandle,IAccessibleObject=self.IAccessibleObject,IAccessibleChildID=newID)

def _getLineOffsets(self,offset):
		lineNum=self._getLineNumFromOffset(offset)
		start=watchdog.cancellableSendMessage(self.obj.windowHandle,winUser.EM_LINEINDEX,lineNum,0)
		length=watchdog.cancellableSendMessage(self.obj.windowHandle,winUser.EM_LINELENGTH,offset,0)
		end=start+length
		#If we just seem to get invalid line info, calculate manually
		if start<=0 and end<=0 and lineNum<=0 and self._getLineCount()<=0 and self._getStoryLength()>0:
			return super(EditTextInfo,self)._getLineOffsets(offset)
		#Some edit controls that show both line feed and carage return can give a length not including the line feed
		if end<=offset:
			end=offset+1
		#edit controls lye about their line length
		limit=self._getStoryLength()
		while self._getLineNumFromOffset(end)==lineNum and end

if self.obj.editAPIVersion>=2:
			bufLen=((end-start)+1)*2
			if self.obj.isWindowUnicode:
				textRange=TextRangeUStruct()
			else:
				textRange=TextRangeAStruct()
			textRange.chrg.cpMin=start
			textRange.chrg.cpMax=end
			processHandle=self.obj.processHandle
			internalBuf=winKernel.virtualAllocEx(processHandle,None,bufLen,winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
			try:
				textRange.lpstrText=internalBuf
				internalTextRange=winKernel.virtualAllocEx(processHandle,None,ctypes.sizeof(textRange),winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
				try:
					winKernel.writeProcessMemory(processHandle,internalTextRange,ctypes.byref(textRange),ctypes.sizeof(textRange),None)
					res=watchdog.cancellableSendMessage(self.obj.windowHandle,EM_GETTEXTRANGE,0,internalTextRange)
				finally:
					winKernel.virtualFreeEx(processHandle,internalTextRange,0,winKernel.MEM_RELEASE)
				buf=(ctypes.c_byte*bufLen)()
				winKernel.readProcessMemory(processHandle,internalBuf,buf,bufLen,None)
			finally:
				winKernel.virtualFreeEx(processHandle,internalBuf,0,winKernel.MEM_RELEASE)
			if self.obj.isWindowUnicode or (res>1 and (buf[res]!=0 or buf[res+1]!=0)): 
				text=ctypes.cast(buf,ctypes.c_wchar_p).value
			else:
				text=unicode(ctypes.cast(buf,ctypes.c_char_p).value, errors="replace", encoding=locale.getlocale()[1])
			# #4095: Some protected richEdit controls do not hide their password characters.
			# We do this specifically.
			# Note that protected standard edit controls get characters hidden in _getStoryText.
			if text and controlTypes.STATE_PROTECTED in self.obj.states:
				text=u'*'*len(text)
		else:

textRange.chrg.cpMax=end
		processHandle=self.obj.processHandle
		internalBuf=winKernel.virtualAllocEx(processHandle,None,bufLen,winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
		try:
			textRange.lpstrText=internalBuf
			internalTextRange=winKernel.virtualAllocEx(processHandle,None,ctypes.sizeof(textRange),winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
			try:
				winKernel.writeProcessMemory(processHandle,internalTextRange,ctypes.byref(textRange),ctypes.sizeof(textRange),None)
				watchdog.cancellableSendMessage(self.obj.windowHandle,SCI_GETTEXTRANGE,0,internalTextRange)
			finally:
				winKernel.virtualFreeEx(processHandle,internalTextRange,0,winKernel.MEM_RELEASE)
			buf=ctypes.create_string_buffer(bufLen)
			winKernel.readProcessMemory(processHandle,internalBuf,buf,bufLen,None)
		finally:
			winKernel.virtualFreeEx(processHandle,internalBuf,0,winKernel.MEM_RELEASE)
		cp=watchdog.cancellableSendMessage(self.obj.windowHandle,SCI_GETCODEPAGE,0,0)
		if cp==SC_CP_UTF8:
			return unicode(buf.value, errors="replace", encoding="utf-8")
		else:
			return unicode(buf.value, errors="replace", encoding=locale.getlocale()[1])

def _getSelectionOffsets(self):
		if self.obj.editAPIVersion>=1:
			charRange=CharRangeStruct()
			processHandle=self.obj.processHandle
			internalCharRange=winKernel.virtualAllocEx(processHandle,None,ctypes.sizeof(charRange),winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
			try:
				watchdog.cancellableSendMessage(self.obj.windowHandle,EM_EXGETSEL,0, internalCharRange)
				winKernel.readProcessMemory(processHandle,internalCharRange,ctypes.byref(charRange),ctypes.sizeof(charRange),None)
			finally:
				winKernel.virtualFreeEx(processHandle,internalCharRange,0,winKernel.MEM_RELEASE)
			return (charRange.cpMin,charRange.cpMax)
		else:
			start=ctypes.c_uint()
			end=ctypes.c_uint()
			res=watchdog.cancellableSendMessage(self.obj.windowHandle,winUser.EM_GETSEL,ctypes.byref(start),ctypes.byref(end))
			return start.value,end.value

def _getWordOffsets(self,offset):
		if self.obj.editAPIVersion>=2:
			start=watchdog.cancellableSendMessage(self.obj.windowHandle,EM_FINDWORDBREAK,WB_MOVEWORDLEFT,offset)
			end=watchdog.cancellableSendMessage(self.obj.windowHandle,EM_FINDWORDBREAK,WB_MOVEWORDRIGHT,start)
			if end<=offset:
				start=end
				end=watchdog.cancellableSendMessage(self.obj.windowHandle,EM_FINDWORDBREAK,WB_MOVEWORDRIGHT,offset)
			return (start,end)
		else:
			if self._getTextRange(offset,offset+1) in ['\r','\n']:
				return offset,offset+1
			else:
				return super(EditTextInfo,self)._getWordOffsets(offset)

def _get_name(self):
		curIndex=watchdog.cancellableSendMessage(hwndWinamp,WM_WA_IPC,-1,IPC_PLAYLIST_GET_NEXT_SELECTED)
		if curIndex <0:
			return None
		info=fileinfo2()
		info.fileindex=curIndex
		internalInfo=winKernel.virtualAllocEx(self.processHandle,None,sizeof(info),winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
		try:
			winKernel.writeProcessMemory(self.processHandle,internalInfo,byref(info),sizeof(info),None)
			watchdog.cancellableSendMessage(self.windowHandle,WM_WA_IPC,IPC_PE_GETINDEXTITLE,internalInfo)
			winKernel.readProcessMemory(self.processHandle,internalInfo,byref(info),sizeof(info),None)
		finally:
			winKernel.virtualFreeEx(self.processHandle,internalInfo,0,winKernel.MEM_RELEASE)
		# file title is fetched in the current locale encoding.
		# We need to decode it to unicode first. 
		encoding=locale.getlocale()[1]
		fileTitle=info.filetitle.decode(encoding,errors="replace")
		return "%d.\t%s\t%s"%(curIndex+1,fileTitle,info.filelength)

def _setSelectionOffsets(self,start,end):
		if self.obj.editAPIVersion>=1:
			charRange=CharRangeStruct()
			charRange.cpMin=start
			charRange.cpMax=end
			processHandle=self.obj.processHandle
			internalCharRange=winKernel.virtualAllocEx(processHandle,None,ctypes.sizeof(charRange),winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
			try:
				winKernel.writeProcessMemory(processHandle,internalCharRange,ctypes.byref(charRange),ctypes.sizeof(charRange),None)
				watchdog.cancellableSendMessage(self.obj.windowHandle,EM_EXSETSEL,0, internalCharRange)
			finally:
				winKernel.virtualFreeEx(processHandle,internalCharRange,0,winKernel.MEM_RELEASE)
		else:
			watchdog.cancellableSendMessage(self.obj.windowHandle,winUser.EM_SETSEL,start,end)
		#Make sure the Window is always scrolled to the caret
		watchdog.cancellableSendMessage(self.obj.windowHandle,winUser.EM_SCROLLCARET,0,0)

def _getSelectionOffsets(self):
		if self.obj.editAPIVersion>=1:
			charRange=CharRangeStruct()
			processHandle=self.obj.processHandle
			internalCharRange=winKernel.virtualAllocEx(processHandle,None,ctypes.sizeof(charRange),winKernel.MEM_COMMIT,winKernel.PAGE_READWRITE)
			try:
				watchdog.cancellableSendMessage(self.obj.windowHandle,EM_EXGETSEL,0, internalCharRange)
				winKernel.readProcessMemory(processHandle,internalCharRange,ctypes.byref(charRange),ctypes.sizeof(charRange),None)
			finally:
				winKernel.virtualFreeEx(processHandle,internalCharRange,0,winKernel.MEM_RELEASE)
			return (charRange.cpMin,charRange.cpMax)
		else:
			start=ctypes.c_uint()
			end=ctypes.c_uint()
			res=watchdog.cancellableSendMessage(self.obj.windowHandle,winUser.EM_GETSEL,ctypes.byref(start),ctypes.byref(end))
			return start.value,end.value