https://bugs.winehq.org/show_bug.cgi?id=53017
--- Comment #1 from François Gouget fgouget@codeweavers.com --- Running user32:monitor with WINEDEBUG=+heap I do get a pretty suspicious looking error, right after the ChangeDisplaySettingsExA(...dm3...) call:
0138:err:heap:validate_free_block heap 00130000, block 00133A40: free block overwritten
This error also goes away if I skip the test_ChangeDisplaySettingsEx() call.