I am not using pythonw.exe, it is the option users prefer to run the program. 

pythonw.exe is a binary, how do you propose to patch that? Or is it translated to .exe with RPython?


Can you be more specific  what shell  does not work correctly, what exactly does not work correctly, and what is the backward-incompatible behaviour that you want to avoid?

pythonw.exe is meant to suppresses the terminal window on startup (console window to be exact), but not to kill vital streams for an application. I posted links Spyder IDE source to show how it should be done.