FIX: close_connect

[GuillaumeFavelier]

Some functions need to be called before the closing event (i.e: dialog, ...etc) and some after (qt object cleanup). This PR adds a bit of flexibility to the GUI API to do just that.

Locally, it solves the issue with doc building.

Traceback (most recent call last):
  File "/home/guillaume/source/anaconda3/envs/mne-py38/lib/python3.8/site-packages/sphinx/events.py", line 101, in emit
    results.append(listener.handler(self.app, *args))
  File "/home/guillaume/source/sphinx-gallery/sphinx_gallery/gen_gallery.py", line 464, in generate_gallery_rst
    generate_dir_rst(src_dir, target_dir, gallery_conf,
  File "/home/guillaume/source/sphinx-gallery/sphinx_gallery/gen_rst.py", line 399, in generate_dir_rst
    intro, title, cost = generate_file_rst(
  File "/home/guillaume/source/sphinx-gallery/sphinx_gallery/gen_rst.py", line 1031, in generate_file_rst
    clean_modules(gallery_conf, fname, 'after')
  File "/home/guillaume/source/sphinx-gallery/sphinx_gallery/scrapers.py", line 596, in clean_modules
    reset_module(gallery_conf, fname, when=when)
  File "/home/guillaume/source/mne-python/doc/conf.py", line 341, in __call__
    _assert_no_instances(Brain, when)  # calls gc.collect()
  File "/home/guillaume/source/mne-python/mne/utils/misc.py", line 368, in _assert_no_instances
    assert n == 0, f'\n{n} {cls.__name__} @ {when}:\n' + '\n'.join(ref)
AssertionError: 
4 Brain @ mne/conf.py:Resetter.__call__:after:10_ieeg_localize.py:
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f6987b9c460>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f698d666b80>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f6987b0f520>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f698d6665e0>>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/guillaume/source/anaconda3/envs/mne-py38/lib/python3.8/site-packages/sphinx/cmd/build.py", line 276, in build_main
    app = Sphinx(args.sourcedir, args.confdir, args.outputdir,
  File "/home/guillaume/source/anaconda3/envs/mne-py38/lib/python3.8/site-packages/sphinx/application.py", line 270, in __init__
    self._init_builder()
  File "/home/guillaume/source/anaconda3/envs/mne-py38/lib/python3.8/site-packages/sphinx/application.py", line 328, in _init_builder
    self.events.emit('builder-inited')
  File "/home/guillaume/source/anaconda3/envs/mne-py38/lib/python3.8/site-packages/sphinx/events.py", line 109, in emit
    raise ExtensionError(__("Handler %r for event %r threw an exception") %
sphinx.errors.ExtensionError: Handler <function generate_gallery_rst at 0x7f69f256de50> for event 'builder-inited' threw an exception (exception: 
4 Brain @ mne/conf.py:Resetter.__call__:after:10_ieeg_localize.py:
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f6987b9c460>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f698d666b80>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f6987b0f520>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f698d6665e0>>)

Extension error (sphinx_gallery.gen_gallery):
Handler <function generate_gallery_rst at 0x7f69f256de50> for event 'builder-inited' threw an exception (exception: 
4 Brain @ mne/conf.py:Resetter.__call__:after:10_ieeg_localize.py:
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f6987b9c460>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f698d666b80>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f6987b0f520>>
Brain._cleaned = True
method: <bound method Brain._clean of <mne.viz._brain._brain.Brain object at 0x7f698d6665e0>>)
make: *** [Makefile:60: html_dev-pattern] Error 2

The issue with Brain was related to _RenderWindow not being reset, indeed a regression from #10305
cc @larsoner

[larsoner]

Locally it does fix the two examples that have been failing, I pushed a commit to touch those so that CircleCI can verify it, then I'll merge. Thanks in advance @GuillaumeFavelier !

[larsoner]

Thanks for the quick fix @GuillaumeFavelier !