https://bugs.winehq.org/show_bug.cgi?id=54988
--- Comment #7 from Andrew Church achurch+wine@achurch.org --- As an additional observation, it seems the preedit_done callback is never called at all in my environment, and thus the NtPostUserMessage(...,FALSE) call added in the patch has no effect; this could certainly be an issue specific to ATOK. Despite this, the NtPostUserMessage(...,TRUE) call in the preedit_start callback is enough to trigger correct behavior, aside from the IME incorrectly starting active.
I was able to obtain completely correct behavior by commenting out the "if (status != ctx->fOpen)" test in imm32/imm.c:ImmSetOpenStatus() and making that block execute unconditionally. I assume ctx->fOpen is intended to reflect the current IME state, so perhaps that's not getting properly updated under some condition? (Again, I have no background knowledge on imm32 and this is just throwing things at the wall to see what sticks.)
Also just for the record, the issue can be checked without logging into a character by going to the settings menu from the title screen, clicking the Other Settings -> Screenshot Folder -> Change Folder button, and typing in the text field that pops up.