make limited length string in form:
      "the string is very lo...(and 15 more)"

def shorten_string(string, max_width):
    ''' make limited length string in form:
      "the string is very lo...(and 15 more)"
    '''
    string_len = len(string)
    if string_len <= max_width:
        return string
    visible = max_width - 16 - int(log10(string_len))
    # expected suffix len "...(and XXXXX more)"
    if not isinstance(string, unistr):
        visstring = unistr(string[:visible], errors='ignore')
    else:
        visstring = string[:visible]
    return u''.join((visstring, u'...(and ',
                     unistr(string_len - visible), u' more)'))