https://bugs.winehq.org/show_bug.cgi?id=55406
--- Comment #1 from kooldioxide@gmail.com --- Meanwhile I also made a bug report directly on the mIRC forums and their main developer confirmed that the big will be fixed in the next mIRC version.
https://forums.mirc.com/ubbthreads.php/topics/271900/re-mirc-7-74-on-wine-co...
I don't know if you still want to have a look from a Wine perspective or if this bug can be resolved.