[Bug 51474] New: user32:input SendInput() triggers an unexpected message 0x60 on Windows 10 1709

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=51474

Bug ID: 51474
           Summary: user32:input SendInput() triggers an unexpected
                    message 0x60 on Windows 10 1709
           Product: Wine
           Version: 6.10
          Hardware: x86-64
                OS: Windows
            Status: NEW
          Severity: normal
          Priority: P2
         Component: user32
          Assignee: [e-mail]
          Reporter: [e-mail]

Created attachment 70310
  --> https://bugs.winehq.org/attachment.cgi?id=70310
Trace all window handles and 0x60 message

SendInput() triggers an unexpected message 0x60 in test_SendInput() on Windows
10 1709:

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

input.c:4451: Test failed: SendInput triggered unexpected message 0x60

* This failure is almost but not 100% systematic on Windows 10 1709: it
happened 202 times out of 205.
* I could not find any documentation on this 0x60 message.
* But the attached patch shows that:
  - The message is sent to a window belonging to our process.
  - The test did not directly create that window.
  - The window class is UserAdapterWindowClass which seems to be related to IME
despite these machines running in a regular en_US locale.

input.c:4404: 4404 hwnd=0000000000020274
input.c:4474: Test failed: SendInput triggered unexpected message 0x60
input.c:4480: hwnd=0000000000020274 pid=7016 tid=7012 now=64359
input.c:4481: hwnd=0000000000040048 message=0060 wParam=1 lParam=0 time=64359
pt=(512,384)
input.c:4485: wnd: pid=7016 tid=7012 class=22 L"UserAdapterWindowClass" text=0
L""