> Martin: I disagree with the approach of raising a UnicodeEncodeError
> if IDLE can't render the output of a user's program, especially when
> the program would otherwise run without error if ran from outside of
> IDLE.

This is really an independent issue, and I'd appreciate if people would
treat it as such. *This* issue is about IDLE crashing, not about how
Tkinter deals with non-BMP characters.

So if the RPC exception marshalling works, and can resolve this issue,
I'll be ready to commit this and close this issue. Opening another issue
dealing with the more general Tk problem would be fine with me.

I don't *quite* understand what you are proposing. If it is that
Tkinter always replaces non-BMP characters in string objects with
question marks, then I'm opposed. Tkinter can't know whether the
replacement is an acceptable loss or not; errors should never pass
silently.

If you are suggesting that IDLE's write function should write
a question mark instead of raising an exception: perhaps, but
a) I'd rather use REPLACEMENT CHARACTER instead of QUESTION MARK
b) I'd really try to find out first whether Tcl unknowingly
    supports UTF-16, at least for rendering.