Link to issue number:

Fixes #12058

Summary of the issue:

If NVDA is run with wxPython 4.1.1, NVDA-specific key commands (scripts) fail to execute while in a WX popup menu (such as the NVDA menu) or wx message box (such as the NVDA About dialog). Yet, key commands that are not trapped by NVDA (E.g. pressing downArrow in a menu) still work okay.
In recent versions of wxWidgets, if in a menu or message box, calling wxWidget's CallAfter function does not execute the given callback until the menu or message box is dismissed (I.e. the wx main loop is again running). There are some exceptions to this, such as if a key or other input is sent to the application. But of course in the case of trying to execute an NVDA-specific command, NVDA blocks the key from getting to the application and therefore the wx event loop never wakes up.
In wxWidgets, it looks like CallAfter calls QueueEvent, which calls WakeupIdle.
Further investigation shows that queuing any kind of wx event (command, idle etc) does not wake up the wx event loop while in popup menus or message boxes.

Description of how this pull request fixes the issue:

Monkeypatch wx.CallAfter to post a WM_NULL message to our top-level window after calling the original CallAfter, which causes wx's event loop to wake up enough to execute the callback.

Testing strategy:

Note: this pr (nor the py3.8 branch at time of this comment) does not yet specifically use wxPython 4.1.1, thus it is necessary for testing that you first:

• cd to include/wx
• Delete everything in this directory
• Fetch wxPython 4.1.1 into this directory with the command: py -m pip install -t . wxPython==4.1.1
  This pr has so far been tested manually by:
• Starting NVDA
• Executing the ReportTime NVDA script by pressing NVDA+f12 and noting that NVDA speaks the time.
• Opening the NVDA menu with NVDA+n
• Again executing reportTime script with NVDA+f12 and noting that NVDA speaks the time. previous to this pr, if using wxPython 4.1.1, the command would fail to execute at all.
• Open NVDA menu -> Help -> About...
• Again execute reportTime script with NVDA+f12 and note that NVDA speaks the time.
  Unit tests do not apply to this pr as the issue is within wxPython.
  System testing is certainly possible here. But only once wxPython 4.1.1 is in NVDA.

Known issues with pull request:

None.

Change log entry:

None needed.

Code Review Checklist:

This checklist is a reminder of things commonly forgotten in a new PR.
Authors, please do a self-review and confirm you have considered the following items.
Mark items you have considered by checking them.
You can do this when editing the Pull request description with an x: [ ] becomes [x].
You can also check the checkboxes after the PR is created.

• Pull Request description is up to date.
• Unit tests.
• System (end to end) tests.
• Manual tests.
• User Documentation.
• Change log entry.
• Context sensitive help for GUI changes.