Lots of times I want to use Idle sort of like a
Mathematica notebook but for Python.  That is, I want
to enter some code and interactively run it, edit it,
run it some more, etc.  Then, at the end, I typically
don't want to save it.  It's like doing a calculation
on scratch paper and throwing away the paper after
finding the answer.

It's a bit of a pain to have to explicitly save such
code in a file, going through the whole file dialog,
after launching to a Python editor window.  Most word
processors will generate an automatic filename like
"Untitled", or "Untitled-1", "Untitled-2", etc., if
"Untitled" already exists.  That makes the dialog a bit
more streamlined.

It would be nice if this type of operation were easier
in IDLE.  I'm not sure of the exact best way.  Here are
some:

1) Have a default filename ("Untitled-<number>.py" for
example) that saves to the user's home dir, or
home/.idle, or maybe some configurable place.  User
could click to confirm (that's probably the easiest) or
IDLE could display some kind of message (preferable)
that doesn't need user interaction.  IDLE has no status
bar right now so maybe it would need one in order to
display such a message conveniently.

I guess the message could be displayed in the Python
shell (by sending an appropriate print statement to the
subprocess) if the user saves by hitting F5 to run the
program.

2) (this is perhaps questionable) The default place to
save the file could be in /tmp.  On hitting F5, the
Python shell would print a message noting that the file
was only in /tmp and hadn't been saved anyplace permanent.