Perform widget rendering, but do not print anything.

def _render_content(self, content, **settings):
        """
        Perform widget rendering, but do not print anything.
        """
        result = []
        columns = settings[self.SETTING_COLUMNS]

        # Format each table cell into string.
        (columns, content) = self.table_format(columns, content)

        # Enumerate each table row.
        if settings[self.SETTING_FLAG_ENUMERATE]:
            (columns, content) = self.table_enumerate(columns, content)

        # Calculate the dimensions of each table column.
        dimensions = self.table_measure(columns, content)

        # Display table header.
        sb = {k: settings[k] for k in (self.SETTING_BORDER_STYLE, self.SETTING_BORDER_FORMATING)}
        result.append(self.fmt_border(dimensions, 't', **sb))
        if settings[self.SETTING_FLAG_HEADER]:
            s = {k: settings[k] for k in (self.SETTING_FLAG_PLAIN, self.SETTING_BORDER_STYLE, self.SETTING_BORDER_FORMATING)}
            s[self.SETTING_TEXT_FORMATING] = settings[self.SETTING_HEADER_FORMATING]
            result.append(self.fmt_row_header(columns, dimensions, **s))
            result.append(self.fmt_border(dimensions, 'm', **sb))

        # Display table body.
        for row in content:
            s = {k: settings[k] for k in (self.SETTING_FLAG_PLAIN, self.SETTING_BORDER_STYLE, self.SETTING_BORDER_FORMATING)}
            s[self.SETTING_TEXT_FORMATING] = settings[self.SETTING_TEXT_FORMATING]
            result.append(self.fmt_row(columns, dimensions, row, **s))

        # Display table footer
        result.append(self.fmt_border(dimensions, 'b', **sb))
        return result