I am guessing that because the extension could be either .py or .pyw, the initial save does not add either but forces the user to type one or the other. I find this annoying too, so I am thinking about separating the choices and see if .py, .pyw, and maybe .txt can be automatically added if not written, while avoiding '.py.py', etc. Hence the change of issue title and type. (Note to self: make sure this is not a duplicate.)