Internal JavaScript Error on closing windows in Mentat

[arun babu]

I upgraded Mentat to 5.1.23 and found that edited tiddlers are not being able to be saved. So I changed the $:/core/ui/EditTemplate to initial version's. Now tiddlers can be saved, but whenever i try to close a window in mentat, it shows internal javascript error. 

I know that the creator of mentat is no longer maintaining it. But if anyone here in google  groups is using upgraded mentat, please help