[Bug 54406] New: user32:msg - test_unicode_wm_char() sometimes gets an unexpected WM_DWMNCRENDERINGCHANGED message on Windows 10+

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=54406

Bug ID: 54406
           Summary: user32:msg - test_unicode_wm_char() sometimes gets an
                    unexpected WM_DWMNCRENDERINGCHANGED message on Windows
                    10+
           Product: Wine
           Version: unspecified
          Hardware: x86-64
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: user32
          Assignee: [e-mail]
          Reporter: [e-mail]

user32:msg - test_unicode_wm_char() sometimes gets an unexpected
WM_DWMNCRENDERINGCHANGED message on Windows 10+:

msg.c:16001: Test failed: unexpected message 31f
msg.c:16002: Test failed: bad wparam 1
msg.c:16008: Test failed: unicode WM_CHAR: 0: the msg sequence is not complete:
expected 0102 - actual 0000
msg.c:16008: Failed sequence unicode WM_CHAR:
msg.c:16008:   0: expected: msg 0102 - actual: nothing

See https://test.winehq.org/data/patterns.html#user32:msg

Where:
031f == WM_DWMNCRENDERINGCHANGED

The first instance happened on 2022-11-08 and there has only been about one
instance per month since.

This looks like some previous test did something that caused the non-client
rendering policy to change but did not wait for this message to be sent and
processed by all windows before continuing. So then which test gets impacted is
up to timing.

dxgi:dxgi has also been getting this message for a long time (see bug 53229).