def format_paragraph_event(self, event, limit=None):
        """Formats paragraph to a max width specified in idleConf.

        If text is selected, format_paragraph_event will start breaking lines
        at the max width, starting from the beginning selection.

        If no text is selected, format_paragraph_event uses the current
        cursor location to determine the paragraph (lines of text surrounded
        by blank lines) and formats it.

        The length limit parameter is for testing with a known value.
        """
        if limit is None:
            # The default length limit is that defined by pep8
            limit = idleConf.GetOption(
                'extensions', 'FormatParagraph', 'max-width',
                type='int', default=72)
        text = self.editwin.text
        first, last = self.editwin.get_selection_indices()
        if first and last:
            data = text.get(first, last)
            comment_header = get_comment_header(data)
        else:
            first, last, comment_header, data = \
                    find_paragraph(text, text.index("insert"))
        if comment_header:
            newdata = reformat_comment(data, limit, comment_header)
        else:
            newdata = reformat_paragraph(data, limit)
        text.tag_remove("sel", "1.0", "end")

        if newdata != data:
            text.mark_set("insert", first)
            text.undo_block_start()
            text.delete(first, last)
            text.insert(first, newdata)
            text.undo_block_stop()
        else:
            text.mark_set("insert", last)
        text.see("insert")
        return "break"