Hi Zhiyi,
I fixed up a patch here, based on the MR you mentioned: https://testbot.winehq.org/GetFile.pl?JobKey=138698&StepKey=1
The tests succeed on new win10 versions but fail in various ways on win7, win8 and early win10. Info from google seems to suggest that the undocumented api's change from version to version, see for example https://stackoverflow.com/questions/53501268/win10-dark-theme-how-to-use-in-...
So I copied and modified a version-check from dlls/schedsvc/rpcapi.c to skip the tests on early winversions. There are still test failures but they seem to happen in ShouldSystemUseDarkMode.
Test results at: https://testbot.winehq.org/JobDetails.pl?Key=138698