Handle mouse input (click column header to sort)

[kasuganosoras]

点击任何项的名称将会崩溃

Traceback (most recent call last):
  File "/usr/local/bin/pingtop", line 10, in <module>
    sys.exit(multi_ping())
  File "/usr/local/lib64/python3.6/site-packages/click/core.py", line 764, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib64/python3.6/site-packages/click/core.py", line 717, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib64/python3.6/site-packages/click/core.py", line 956, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib64/python3.6/site-packages/click/core.py", line 555, in invoke
    return callback(*args, **kwargs)
  File "/usr/local/bin/pingtop.py", line 370, in multi_ping
    mainloop.run()
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 286, in run
    self._run()
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 384, in _run
    self.event_loop.run()
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 788, in run
    self._loop()
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 825, in _loop
    self._watch_files[fd]()
  File "/usr/local/lib64/python3.6/site-packages/urwid/raw_display.py", line 404, in <lambda>
    event_loop, callback, self.get_available_raw_input())
  File "/usr/local/lib64/python3.6/site-packages/urwid/raw_display.py", line 502, in parse_input
    callback(processed, processed_codes)
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 411, in _update
    self.process_input(keys)
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 517, in process_input
    something_handled |= bool(self.unhandled_input(k))
  File "/usr/local/lib64/python3.6/site-packages/urwid/main_loop.py", line 563, in unhandled_input
    return self._unhandled_input(input)
  File "/usr/local/bin/pingtop.py", line 217, in global_input
    elif key.upper() in sort_keys:
AttributeError: 'tuple' object has no attribute 'upper'