Don't require synced traits with VideoEditor

[jwiggins]

@corranwebster This is an implementation of what I believe you described as the intended use of Editor synced traits, applied to VideoEditor.

[jwiggins]

Care to take another look? I think I like the code this way (using ContextValue) a bit better but it's not quite right yet. Playing with the demo, it seems like the state isn't staying synchronized.

[corranwebster]

This pretty much matches my version, so whichever we go with is fine.

[rahulporuri]

CI failed with what looks like an intermittent failure. restarting job now.

test_base_url_changed (traitsui.tests.editors.test_html_editor.TestHTMLEditor) ... Fatal Python error: Illegal instruction

Current thread 0x00007f2fe2867740 (most recent call first):
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/traitsui/testing/_gui.py", line 36 in process_cascade_events
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/traitsui/testing/tester/ui_tester.py", line 116 in create_ui
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/contextlib.py", line 88 in __exit__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/traitsui/tests/editors/test_html_editor.py", line 253 in test_base_url_changed
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/case.py", line 605 in run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/case.py", line 653 in __call__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 122 in run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 84 in __call__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 122 in run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 84 in __call__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 122 in run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 84 in __call__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 122 in run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/suite.py", line 84 in __call__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/runner.py", line 176 in run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/main.py", line 256 in runTests
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/main.py", line 95 in __init__
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/unittest/__main__.py", line 18 in <module>
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/coverage/execfile.py", line 183 in run_python_file
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/coverage/execfile.py", line 113 in run_python_module
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/coverage/cmdline.py", line 627 in do_run
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/coverage/cmdline.py", line 483 in command_line
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/coverage/cmdline.py", line 756 in main
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/site-packages/coverage/__main__.py", line 8 in <module>
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/runpy.py", line 85 in _run_code
  File "/home/runner/work/traitsui/traitsui/.edm/envs/traitsui-test-3.6-pyside2/lib/python3.6/runpy.py", line 193 in _run_module_as_main
Command '['edm', 'run', '-e', 'traitsui-test-3.6-pyside2', '--', 'python', '-X', 'faulthandler', '-W', 'default', '-m', 'coverage', 'run', '-p', '-m', 'unittest', 'discover', '-v', 'traitsui']' returned non-zero exit status 252.

[corranwebster]

This is failing consistently on an unrelated test.

[jwiggins]

What's needed to move forward here?

[corranwebster]

I think confirmation from the internal users who originally raised the issue that this solves it would be good.

I also think the ETS team are dealing with some non-work related issues today.

I'm good with the current state and if it's urgent to get it merged I can approve.

[jwiggins]

Not urgent. I'll reach out to the affected users to solicit their feedback.

[mdsmarte]

Tested in context of our project and verified working as expected. Thanks for making the fix!