Problem identification

"SJIS/JIS conversion" option situated in Options/Messages turns on the conversion for every information sent and received regarding the encoding the user uses in current window. It tries to find patterns of Shift-JIS in every piece of information, converts it to JIS and sends it to the server.

Reproduction

In any channel, set the encoding to Japanese (you'd need some Japanese font for that of course) and enable the SJIS/JIS conversion. Now, in some other channel of Cyrillic encoding, enter "да" (0xE4 0xE0 in widows-1251) in the input field ("да" means "yes" in English). On the other side, users with SJIS/JIS conversion off will see "$Bhb(B" (minus some ANSI codes), which is JIS for Shift-JIS hieroglyph "萵", or 0xE4 0xE0, which means "lettuce"--something pretty far away from "yes".

Possible solution

For adding some kind of option to allow users to turn SJIS/JIS conversion on in the /font dialog may possibly ruin some user scripts, the "Use SJIS/JIS convesion: on / default" option could be placed instead, allowing users to change the default setting in the Options/Messages dialog, like it is done with Unicode.

Apparently this bug was missed, though it was confirmed, hence i am writing this post on the advice of one of the ops of the EFNET #mirc channel.