ParenMatch sometimes misinterprets closing parenthesis
because it is given a bad keysym. The real bug is
probably somewhere in the event handling mechanism or
something.

Somehow the text widget gets the right signal and the
appropriate closing paren is written there.

This simple patch checks the last inserted character in
the text widget insted of the generated keysym, and
acts accordingly.

Since the function where the workaround is applied
reads text from the text widget from the same index
anyways, I think this workaround is actually much
cleaner than checking the keysym!

Works like a charm on my Python2.4 WinXP installation.