This returns a copy of the screen as a unicode string with an ASCII
        text box around the screen border. This is similar to
        __str__/__unicode__ except that it adds a box.

def pretty (self):
        '''This returns a copy of the screen as a unicode string with an ASCII
        text box around the screen border. This is similar to
        __str__/__unicode__ except that it adds a box.'''

        top_bot = u'+' + u'-'*self.cols + u'+\n'
        return top_bot + u'\n'.join([u'|'+line+u'|' for line in unicode(self).split(u'\n')]) + u'\n' + top_bot