'Ensures all lines on a screen have proper width (:attr:`columns`).
Extra characters are truncated, missing characters are filled
with whitespace.'

def __after__(self, command):

    if (command in [u'prev_page', u'next_page']):
        for (idx, line) in enumerate(self.buffer):
            if (len(line) > self.columns):
                self.buffer[idx] = line[:self.columns]
            elif (len(line) < self.columns):
                self.buffer[idx] = (line + take((self.columns - len(line)), self.default_line))
    self.cursor.hidden = (not ((abs((self.history.position - self.history.size)) < self.lines) and (mo.DECTCEM in self.mode)))
    super(HistoryScreen, self).__after__(command)
