Improve invoke() method to avoid hang problems

This ia a new issue based in the discussion that started in https://github.com/pywinauto/pywinauto/issues/865

Basically, sometimes invoke() is raising a generic exception.

>>> loginButton.click()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Users\diego.queiroz\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.8_qbz5n2kfra8p0\LocalCache\local-packages\Python38\site-packages\pywinauto\controls\uia_controls.py", line 121, in click
    self.invoke()
  File "C:\Users\diego.queiroz\AppData\Local\Packages\PythonSoftwareFoundation.Python.3.8_qbz5n2kfra8p0\LocalCache\local-packages\Python38\site-packages\pywinauto\controls\uiawrapper.py", line 513, in invoke
    self.iface_invoke.Invoke()
_ctypes.COMError: (-2147220991, 'event cannot call any subscribers', (None, None, None, 0, None))

Despite the exception, the button is clicked as expected. The current workaround is to just ignore the exception, as follows:

try:
  loginButton.click()
except:
  pass # ignore

# script continues here

This may be happening because the application is not returning in a timely manner (indeed, the application I am testing freezes for a second when I click the login button). Probably a improvement like a configurable timeout may solve this problem.

Also, it would be interesting to raise a more specific exception when an error like this happens.

@vasily-v-ryabov said:

Sometimes we also face with hang problem when calling .invoke() (.click() is an alias of .invoke() for ButtonWrapper). It means we need to create a separate thread with some timeout and print a warning if it is timed out. This is also separate issue, but we can combine it in one issue since it is all in .invoke() method.

[DiegoQueiroz]

@celsolarussa The current workaround is to just ignore the exception, as shown in the first message.

try:
  loginButton.click()
except:
  pass # ignore exception

# script continues here

[vasily-v-ryabov]

We will try to improve backward compatibility before release. But this particular feature is implemented and I’m closing the issue to help us tracking progress for 0.7.0 milestone. Thanks for understanding! I will notify when new release is out.