PyOS_InputHook is a pointer to a function to be called
periodically when Python is idle. It is used, for
example, to get messages delivered to graphics windows.
If I compile Python from source (which uses
Modules/readline.c), PyOS_InputHook is called ten times
per second. However, with the Windows-version of
Python, PyOS_InputHook is called only once for each
command typed by the user. It seems that the problem
resides in Parser/myreadline.c (which I presume is used
for the Windows-version of Python):

if (PyOS_InputHook != NULL)
       (void)(PyOS_InputHook)();
...
p = fgets(buf, len, fp);

Python idles at "fgets", but PyOS_InputHook is not
being called while Python is idle.

The attached patch solves this problem by using the
"select" function, basically in the same way as what is
in Module/readline.c. I don't know how to compile
Python for Windows, so I wasn't able to test this patch.