The latest x.y docs are available at docs.python.org/x.y, such ashttps://docs.python.org/3.4/faq/gui.htmlI was not aware of this undocumented method of the undocumented tkapp class.  It is not available on Windows, and the FAQ should say so. FromModules/_tkinter.c: /* Tcl_CreateFileHandler() changed several times; these macros deal with the  messiness.  In Tcl 8.0 and later, it is not available on Windows (and on  Unix, only because Jack added it back); when available on Windows, it only applies to sockets. */Current _tkinter only supports 8.4+. The messiness still appears in the asyncio design.'createfile' does not appear on the pydoc page for tkinter; directly using createfilehandle seems to be the only access.